refactor: complete module-driven architecture migration

This commit completes the migration to a fully module-driven architecture:

## Models Migration
- Moved all domain models from models/database/ to their respective modules:
  - tenancy: User, Admin, Vendor, Company, Platform, VendorDomain, etc.
  - cms: MediaFile, VendorTheme
  - messaging: Email, VendorEmailSettings, VendorEmailTemplate
  - core: AdminMenuConfig
- models/database/ now only contains Base and TimestampMixin (infrastructure)

## Schemas Migration
- Moved all domain schemas from models/schema/ to their respective modules:
  - tenancy: company, vendor, admin, team, vendor_domain
  - cms: media, image, vendor_theme
  - messaging: email
- models/schema/ now only contains base.py and auth.py (infrastructure)

## Routes Migration
- Moved admin routes from app/api/v1/admin/ to modules:
  - menu_config.py -> core module
  - modules.py -> tenancy module
  - module_config.py -> tenancy module
- app/api/v1/admin/ now only aggregates auto-discovered module routes

## Menu System
- Implemented module-driven menu system with MenuDiscoveryService
- Extended FrontendType enum: PLATFORM, ADMIN, VENDOR, STOREFRONT
- Added MenuItemDefinition and MenuSectionDefinition dataclasses
- Each module now defines its own menu items in definition.py
- MenuService integrates with MenuDiscoveryService for template rendering

## Documentation
- Updated docs/architecture/models-structure.md
- Updated docs/architecture/menu-management.md
- Updated architecture validation rules for new exceptions

## Architecture Validation
- Updated MOD-019 rule to allow base.py in models/schema/
- Created core module exceptions.py and schemas/ directory
- All validation errors resolved (only warnings remain)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/modules/tenancy/models/admin.py

@@ -0,0 +1,205 @@
+# app/modules/tenancy/models/admin.py
+"""
+Admin-specific database models.
+
+This module provides models for:
+- Admin audit logging (compliance and security tracking)
+- Admin notifications (system alerts and warnings)
+- Platform settings (global configuration)
+- Platform alerts (system-wide issues)
+- Application logs (critical events logging)
+"""
+
+from sqlalchemy import (
+    JSON,
+    Boolean,
+    Column,
+    DateTime,
+    ForeignKey,
+    Integer,
+    String,
+    Text,
+)
+from sqlalchemy.orm import relationship
+
+from app.core.database import Base
+from models.database.base import TimestampMixin
+
+
+class AdminAuditLog(Base, TimestampMixin):
+    """
+    Track all admin actions for compliance and security.
+
+    Separate from regular audit logs - focuses on admin-specific operations
+    like vendor creation, user management, and system configuration changes.
+    """
+
+    __tablename__ = "admin_audit_logs"
+
+    id = Column(Integer, primary_key=True, index=True)
+    admin_user_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True)
+    action = Column(
+        String(100), nullable=False, index=True
+    )  # create_vendor, delete_vendor, etc.
+    target_type = Column(
+        String(50), nullable=False, index=True
+    )  # vendor, user, import_job, setting
+    target_id = Column(String(100), nullable=False, index=True)
+    details = Column(JSON)  # Additional context about the action
+    ip_address = Column(String(45))  # IPv4 or IPv6
+    user_agent = Column(Text)
+    request_id = Column(String(100))  # For correlating with application logs
+
+    # Relationships
+    admin_user = relationship("User", foreign_keys=[admin_user_id])
+
+    def __repr__(self):
+        return f"<AdminAuditLog(id={self.id}, action='{self.action}', target={self.target_type}:{self.target_id})>"
+
+
+# AdminNotification has been moved to app/modules/messaging/models/admin_notification.py
+# It's re-exported via models/database/__init__.py for backwards compatibility
+
+
+class AdminSetting(Base, TimestampMixin):
+    """
+    Platform-wide admin settings and configuration.
+
+    Stores global settings that affect the entire platform, different from
+    vendor-specific settings. Supports encryption for sensitive values.
+
+    Examples:
+    - max_vendors_allowed
+    - maintenance_mode
+    - default_vendor_trial_days
+    - smtp_settings
+    - stripe_api_keys (encrypted)
+    """
+
+    __tablename__ = "admin_settings"
+
+    id = Column(Integer, primary_key=True, index=True)
+    key = Column(String(100), unique=True, nullable=False, index=True)
+    value = Column(Text, nullable=False)
+    value_type = Column(String(20), default="string")  # string, integer, boolean, json
+    category = Column(
+        String(50), index=True
+    )  # system, security, marketplace, notifications
+    description = Column(Text)
+    is_encrypted = Column(Boolean, default=False)
+    is_public = Column(Boolean, default=False)  # Can be exposed to frontend?
+    last_modified_by_user_id = Column(Integer, ForeignKey("users.id"), nullable=True)
+
+    # Relationships
+    last_modified_by = relationship("User", foreign_keys=[last_modified_by_user_id])
+
+    def __repr__(self):
+        return f"<AdminSetting(key='{self.key}', category='{self.category}')>"
+
+
+class PlatformAlert(Base, TimestampMixin):
+    """
+    System-wide alerts that admins need to be aware of.
+
+    Tracks platform issues, performance problems, security incidents,
+    and other system-level concerns that require admin attention.
+    """
+
+    __tablename__ = "platform_alerts"
+
+    id = Column(Integer, primary_key=True, index=True)
+    alert_type = Column(
+        String(50), nullable=False, index=True
+    )  # security, performance, capacity, integration
+    severity = Column(
+        String(20), nullable=False, index=True
+    )  # info, warning, error, critical
+    title = Column(String(200), nullable=False)
+    description = Column(Text)
+    affected_vendors = Column(JSON)  # List of affected vendor IDs
+    affected_systems = Column(JSON)  # List of affected system components
+    is_resolved = Column(Boolean, default=False, index=True)
+    resolved_at = Column(DateTime, nullable=True)
+    resolved_by_user_id = Column(Integer, ForeignKey("users.id"), nullable=True)
+    resolution_notes = Column(Text)
+    auto_generated = Column(Boolean, default=True)  # System-generated vs manual
+    occurrence_count = Column(Integer, default=1)  # Track repeated occurrences
+    first_occurred_at = Column(DateTime, nullable=False)
+    last_occurred_at = Column(DateTime, nullable=False)
+
+    # Relationships
+    resolved_by = relationship("User", foreign_keys=[resolved_by_user_id])
+
+    def __repr__(self):
+        return f"<PlatformAlert(id={self.id}, type='{self.alert_type}', severity='{self.severity}')>"
+
+
+class AdminSession(Base, TimestampMixin):
+    """
+    Track admin login sessions for security monitoring.
+
+    Helps identify suspicious login patterns, track concurrent sessions,
+    and enforce session policies for admin users.
+    """
+
+    __tablename__ = "admin_sessions"
+
+    id = Column(Integer, primary_key=True, index=True)
+    admin_user_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True)
+    session_token = Column(String(255), unique=True, nullable=False, index=True)
+    ip_address = Column(String(45), nullable=False)
+    user_agent = Column(Text)
+    login_at = Column(DateTime, nullable=False, index=True)
+    last_activity_at = Column(DateTime, nullable=False)
+    logout_at = Column(DateTime, nullable=True)
+    is_active = Column(Boolean, default=True, index=True)
+    logout_reason = Column(String(50))  # manual, timeout, forced, suspicious
+
+    # Relationships
+    admin_user = relationship("User", foreign_keys=[admin_user_id])
+
+    def __repr__(self):
+        return f"<AdminSession(id={self.id}, admin_user_id={self.admin_user_id}, is_active={self.is_active})>"
+
+
+class ApplicationLog(Base, TimestampMixin):
+    """
+    Application-level logs stored in database for critical events.
+
+    Stores WARNING, ERROR, and CRITICAL level logs for easy searching,
+    filtering, and compliance. INFO and DEBUG logs are kept in files only.
+    """
+
+    __tablename__ = "application_logs"
+
+    id = Column(Integer, primary_key=True, index=True)
+    timestamp = Column(DateTime, nullable=False, index=True)
+    level = Column(String(20), nullable=False, index=True)  # WARNING, ERROR, CRITICAL
+    logger_name = Column(String(200), nullable=False, index=True)
+    module = Column(String(200))
+    function_name = Column(String(100))
+    line_number = Column(Integer)
+    message = Column(Text, nullable=False)
+    exception_type = Column(String(200))
+    exception_message = Column(Text)
+    stack_trace = Column(Text)
+    request_id = Column(String(100), index=True)  # For correlating logs
+    user_id = Column(Integer, ForeignKey("users.id"), nullable=True, index=True)
+    vendor_id = Column(Integer, ForeignKey("vendors.id"), nullable=True, index=True)
+    context = Column(JSON)  # Additional context data
+
+    # Relationships
+    user = relationship("User", foreign_keys=[user_id])
+    vendor = relationship("Vendor", foreign_keys=[vendor_id])
+
+    def __repr__(self):
+        return f"<ApplicationLog(id={self.id}, level='{self.level}', logger='{self.logger_name}')>"
+
+
+__all__ = [
+    "AdminAuditLog",
+    "AdminSetting",
+    "PlatformAlert",
+    "AdminSession",
+    "ApplicationLog",
+]