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/company.py

@@ -0,0 +1,109 @@
+# app/modules/tenancy/models/company.py
+"""
+Company model representing the business entity that owns one or more vendor brands.
+
+A Company represents the legal/business entity with contact information,
+while Vendors represent the individual brands/storefronts operated by that company.
+"""
+
+from sqlalchemy import Boolean, Column, ForeignKey, Integer, String, Text
+from sqlalchemy.orm import relationship
+
+from app.core.database import Base
+from models.database.base import TimestampMixin
+
+
+class Company(Base, TimestampMixin):
+    """
+    Represents a company (business entity) in the system.
+
+    A company owns one or more vendor brands. All business/contact information
+    is stored at the company level to avoid duplication.
+    """
+
+    __tablename__ = "companies"
+
+    # ========================================================================
+    # Basic Information
+    # ========================================================================
+    id = Column(Integer, primary_key=True, index=True)
+    """Unique identifier for the company."""
+
+    name = Column(String, nullable=False, index=True)
+    """Company legal/business name."""
+
+    description = Column(Text)
+    """Optional description of the company."""
+
+    # ========================================================================
+    # Ownership
+    # ========================================================================
+    owner_user_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    """Foreign key to the user who owns this company."""
+
+    # ========================================================================
+    # Contact Information
+    # ========================================================================
+    contact_email = Column(String, nullable=False)
+    """Primary business contact email."""
+
+    contact_phone = Column(String)
+    """Business phone number."""
+
+    website = Column(String)
+    """Company website URL."""
+
+    # ========================================================================
+    # Business Details
+    # ========================================================================
+    business_address = Column(Text)
+    """Physical business address."""
+
+    tax_number = Column(String)
+    """Tax/VAT registration number."""
+
+    # ========================================================================
+    # Status Flags
+    # ========================================================================
+    is_active = Column(Boolean, default=True, nullable=False)
+    """Whether the company is active. Affects all associated vendors."""
+
+    is_verified = Column(Boolean, default=False, nullable=False)
+    """Whether the company has been verified by platform admins."""
+
+    # ========================================================================
+    # Relationships
+    # ========================================================================
+    owner = relationship("User", back_populates="owned_companies")
+    """The user who owns this company."""
+
+    vendors = relationship(
+        "Vendor",
+        back_populates="company",
+        cascade="all, delete-orphan",
+        order_by="Vendor.name",
+    )
+    """All vendor brands operated by this company."""
+
+    def __repr__(self):
+        """String representation of the Company object."""
+        return f"<Company(id={self.id}, name='{self.name}', vendors={len(self.vendors) if self.vendors else 0})>"
+
+    # ========================================================================
+    # Helper Properties
+    # ========================================================================
+
+    @property
+    def vendor_count(self) -> int:
+        """Get the number of vendors belonging to this company."""
+        return len(self.vendors) if self.vendors else 0
+
+    @property
+    def active_vendor_count(self) -> int:
+        """Get the number of active vendors belonging to this company."""
+        if not self.vendors:
+            return 0
+        return sum(1 for v in self.vendors if v.is_active)
+
+
+__all__ = ["Company"]