feat: implement comments and activity panel in workspace

- Added CommentsPanel component for managing comments on documents.
- Integrated comment creation, deletion, and resolution functionalities.
- Implemented activity tracking for document interactions.
- Enhanced SketchPage with editing and saving capabilities.
- Introduced template management API endpoints for creating, sharing, and deleting templates.
- Added runtime validation report for frontend and backend.
- Created GettingStartedPanel for user onboarding with template options.
- Implemented Playwright E2E tests for accessibility and export functionality.

backend/app/schemas/collaboration.py

@@ -0,0 +1,44 @@
+from datetime import datetime
+
+from pydantic import BaseModel, Field
+
+
+class CommentCreate(BaseModel):
+    body: str = Field(min_length=1, max_length=5000)
+    parent_id: str | None = None
+
+
+class CommentResponse(BaseModel):
+    id: str
+    document_id: str
+    body: str
+    parent_id: str | None = None
+    author_id: int
+    author_name: str
+    created_at: datetime
+    updated_at: datetime
+    resolved: bool = False
+
+
+class CommentResolveRequest(BaseModel):
+    resolved: bool
+
+
+class NotificationResponse(BaseModel):
+    id: str
+    kind: str
+    message: str
+    document_id: str | None = None
+    comment_id: str | None = None
+    actor_name: str
+    read: bool
+    created_at: datetime
+
+
+class ActivityResponse(BaseModel):
+    id: str
+    document_id: str
+    kind: str
+    message: str
+    actor_name: str
+    created_at: datetime