feat: Add role-based API tokens for Claudia Docs

- Add api_tokens table with role-based access (researcher, developer, viewer)
- Add POST /auth/token/generate endpoint for creating tokens
- Add GET /auth/tokens endpoint for listing user's tokens
- Add DELETE /auth/tokens/{token_id} endpoint for revoking tokens
- Add agent_type field to documents (research, development, general)
- Implement role-based access control for documents:
  - researcher: access to research and general documents
  - developer: access to development and general documents
  - viewer: read-only access
- Update document model and schemas with agent_type field
- Add comprehensive tests for API token functionality
- All existing tests pass (73 total)

app/schemas/auth.py

@@ -30,3 +30,25 @@ class TokenResponse(BaseModel):
 class RefreshResponse(BaseModel):
     access_token: str
     token_type: str = "bearer"
+
+
+class ApiTokenCreate(BaseModel):
+    name: str = Field(..., min_length=1, max_length=255)
+    role: str = Field(..., pattern="^(researcher|developer|viewer)$")
+
+
+class ApiTokenResponse(BaseModel):
+    id: str
+    name: str
+    role: str
+    created_at: datetime
+
+    model_config = {"from_attributes": True}
+
+
+class ApiTokenGenerateResponse(BaseModel):
+    token: str
+    name: str
+    role: str
+
+    model_config = {"from_attributes": True}