refactor: modernize code quality tooling with Ruff

- Replace black, isort, and flake8 with Ruff (all-in-one linter and formatter)
- Add comprehensive pyproject.toml configuration
- Simplify Makefile code quality targets
- Configure exclusions for venv/.venv in pyproject.toml
- Auto-fix 1,359 linting issues across codebase

Benefits:
- Much faster builds (Ruff is written in Rust)
- Single tool replaces multiple tools
- More comprehensive rule set (UP, B, C4, SIM, PIE, RET, Q)
- All configuration centralized in pyproject.toml
- Better import sorting and formatting consistency

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/api/v1/admin/code_quality.py

@@ -4,7 +4,6 @@ RESTful API for architecture validation and violation management
 """
 
 from datetime import datetime
-from typing import Optional
 
 from fastapi import APIRouter, Depends, HTTPException, Query
 from pydantic import BaseModel, Field
@@ -32,7 +31,7 @@ class ScanResponse(BaseModel):
     warnings: int
     duration_seconds: float
     triggered_by: str
-    git_commit_hash: Optional[str]
+    git_commit_hash: str | None
 
     class Config:
         from_attributes = True
@@ -49,13 +48,13 @@ class ViolationResponse(BaseModel):
     file_path: str
     line_number: int
     message: str
-    context: Optional[str]
-    suggestion: Optional[str]
+    context: str | None
+    suggestion: str | None
     status: str
-    assigned_to: Optional[int]
-    resolved_at: Optional[str]
-    resolved_by: Optional[int]
-    resolution_note: Optional[str]
+    assigned_to: int | None
+    resolved_at: str | None
+    resolved_by: int | None
+    resolution_note: str | None
     created_at: str
 
     class Config:
@@ -83,7 +82,7 @@ class AssignViolationRequest(BaseModel):
     """Request model for assigning a violation"""
 
     user_id: int = Field(..., description="User ID to assign to")
-    due_date: Optional[datetime] = Field(None, description="Due date for resolution")
+    due_date: datetime | None = Field(None, description="Due date for resolution")
     priority: str = Field(
         "medium", description="Priority level (low, medium, high, critical)"
     )
@@ -123,7 +122,7 @@ class DashboardStatsResponse(BaseModel):
     by_rule: dict
     by_module: dict
     top_files: list
-    last_scan: Optional[str]
+    last_scan: str | None
 
 
 # API Endpoints
@@ -189,17 +188,17 @@ async def list_scans(
 
 @router.get("/violations", response_model=ViolationListResponse)
 async def list_violations(
-    scan_id: Optional[int] = Query(
+    scan_id: int | None = Query(
         None, description="Filter by scan ID (defaults to latest)"
     ),
-    severity: Optional[str] = Query(
+    severity: str | None = Query(
         None, description="Filter by severity (error, warning)"
     ),
-    status: Optional[str] = Query(
+    status: str | None = Query(
         None, description="Filter by status (open, assigned, resolved, ignored)"
     ),
-    rule_id: Optional[str] = Query(None, description="Filter by rule ID"),
-    file_path: Optional[str] = Query(
+    rule_id: str | None = Query(None, description="Filter by rule ID"),
+    file_path: str | None = Query(
         None, description="Filter by file path (partial match)"
     ),
     page: int = Query(1, ge=1, description="Page number"),