feat(phase-9): implement MVP polishing and closure

T-032: User management admin panel - backend users router with CRUD, frontend UsersPage with modals

T-033: Audit log viewer - backend audit router with filters/pagination, frontend AuditLogPage

T-034: Global error handling - ErrorBoundary, LoadingSpinner, ErrorMessage, Toast components

T-035: Backend tests - pytest setup with SQLite, tests for health/auth/techniques/tests

T-036: Documentation - Updated README with testing section, created docs/API.md

backend/app/routers/audit.py

@@ -0,0 +1,118 @@
+"""Audit log viewer router (admin only)."""
+
+from datetime import datetime
+from typing import Optional
+
+from fastapi import APIRouter, Depends, Query
+from sqlalchemy import func
+from sqlalchemy.orm import Session, joinedload
+
+from app.database import get_db
+from app.dependencies.auth import require_role
+from app.models.audit import AuditLog
+from app.models.user import User
+from app.schemas.audit import AuditLogOut, AuditLogPage
+
+router = APIRouter(prefix="/audit-logs", tags=["audit"])
+
+
+@router.get("", response_model=AuditLogPage)
+def list_audit_logs(
+    user_id: Optional[str] = Query(None, description="Filter by user ID"),
+    action: Optional[str] = Query(None, description="Filter by action type"),
+    entity_type: Optional[str] = Query(None, description="Filter by entity type"),
+    start_date: Optional[datetime] = Query(None, description="Filter by start date"),
+    end_date: Optional[datetime] = Query(None, description="Filter by end date"),
+    offset: int = Query(0, ge=0, description="Number of records to skip"),
+    limit: int = Query(50, ge=1, le=100, description="Max records to return"),
+    db: Session = Depends(get_db),
+    current_user: User = Depends(require_role("admin")),
+):
+    """Return paginated audit logs with optional filters.
+    
+    **Requires admin role.**
+    """
+    query = db.query(AuditLog).options(joinedload(AuditLog.user))
+    
+    # Apply filters
+    if user_id:
+        query = query.filter(AuditLog.user_id == user_id)
+    if action:
+        query = query.filter(AuditLog.action == action)
+    if entity_type:
+        query = query.filter(AuditLog.entity_type == entity_type)
+    if start_date:
+        query = query.filter(AuditLog.timestamp >= start_date)
+    if end_date:
+        query = query.filter(AuditLog.timestamp <= end_date)
+    
+    # Get total count
+    total = query.count()
+    
+    # Get paginated results
+    logs = (
+        query
+        .order_by(AuditLog.timestamp.desc())
+        .offset(offset)
+        .limit(limit)
+        .all()
+    )
+    
+    # Convert to response format with username
+    items = []
+    for log in logs:
+        item = AuditLogOut(
+            id=log.id,
+            user_id=log.user_id,
+            username=log.user.username if log.user else None,
+            action=log.action,
+            entity_type=log.entity_type,
+            entity_id=log.entity_id,
+            timestamp=log.timestamp,
+            details=log.details,
+        )
+        items.append(item)
+    
+    return AuditLogPage(
+        items=items,
+        total=total,
+        offset=offset,
+        limit=limit,
+    )
+
+
+@router.get("/actions", response_model=list[str])
+def list_actions(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(require_role("admin")),
+):
+    """Return a list of distinct action types in the audit log.
+    
+    **Requires admin role.**
+    """
+    actions = (
+        db.query(AuditLog.action)
+        .distinct()
+        .order_by(AuditLog.action)
+        .all()
+    )
+    return [a[0] for a in actions]
+
+
+@router.get("/entity-types", response_model=list[str])
+def list_entity_types(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(require_role("admin")),
+):
+    """Return a list of distinct entity types in the audit log.
+    
+    **Requires admin role.**
+    """
+    types = (
+        db.query(AuditLog.entity_type)
+        .filter(AuditLog.entity_type.isnot(None))
+        .distinct()
+        .order_by(AuditLog.entity_type)
+        .all()
+    )
+    return [t[0] for t in types]