feat: add unified linting scripts and git hooks for code quality enforcement

- Introduced `lint` and `lint-fix` applications in `flake.nix` for unified linting of backend (Python) and frontend (TypeScript/Svelte) code.
- Added `scripts/lint.sh` for manual linting execution.
- Created `scripts/install-hooks.sh` to set up git hooks for automatic linting before commits and optional tests before pushes.
- Updated `README.md` with instructions for using the new linting features and git hooks.

backend/app/database/models/comment.py

@@ -1,6 +1,8 @@
 """Comment model for board comments."""
+
 import uuid
 from datetime import datetime
+
 from sqlalchemy import Boolean, Column, DateTime, ForeignKey, String, Text
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import relationship
@@ -15,7 +17,9 @@ class Comment(Base):
 
     id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
     board_id = Column(UUID(as_uuid=True), ForeignKey("boards.id", ondelete="CASCADE"), nullable=False, index=True)
-    share_link_id = Column(UUID(as_uuid=True), ForeignKey("share_links.id", ondelete="SET NULL"), nullable=True, index=True)
+    share_link_id = Column(
+        UUID(as_uuid=True), ForeignKey("share_links.id", ondelete="SET NULL"), nullable=True, index=True
+    )
     author_name = Column(String(100), nullable=False)
     content = Column(Text, nullable=False)
     position = Column(JSONB, nullable=True)  # Optional canvas position
@@ -28,4 +32,3 @@ class Comment(Base):
 
     def __repr__(self) -> str:
         return f"<Comment(id={self.id}, author={self.author_name})>"
-