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/board.py

@@ -1,6 +1,8 @@
 """Board model for reference boards."""
+
 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
@@ -17,11 +19,7 @@ class Board(Base):
     user_id = Column(UUID(as_uuid=True), ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
     title = Column(String(255), nullable=False)
     description = Column(Text, nullable=True)
-    viewport_state = Column(
-        JSONB,
-        nullable=False,
-        default={"x": 0, "y": 0, "zoom": 1.0, "rotation": 0}
-    )
+    viewport_state = Column(JSONB, nullable=False, default={"x": 0, "y": 0, "zoom": 1.0, "rotation": 0})
     created_at = Column(DateTime, nullable=False, default=datetime.utcnow)
     updated_at = Column(DateTime, nullable=False, default=datetime.utcnow, onupdate=datetime.utcnow)
     is_deleted = Column(Boolean, nullable=False, default=False)
@@ -35,4 +33,3 @@ class Board(Base):
 
     def __repr__(self) -> str:
         return f"<Board(id={self.id}, title={self.title})>"
-