feat: add per-space timezone settings and improve booking management

- Add timezone configuration per space with fallback to system default
- Implement timezone-aware datetime display and editing across frontend
- Add migration for per_space_settings table
- Update booking service to handle timezone conversions properly
- Improve .gitignore to exclude build artifacts
- Add comprehensive testing documentation

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

backend/app/schemas/space.py

@@ -10,6 +10,12 @@ class SpaceBase(BaseModel):
     capacity: int = Field(..., gt=0)
     description: str | None = None
 
+    # Per-space scheduling settings (None = use global default)
+    working_hours_start: int | None = None
+    working_hours_end: int | None = None
+    min_duration_minutes: int | None = None
+    max_duration_minutes: int | None = None
+
 
 class SpaceCreate(SpaceBase):
     """Space creation schema."""
@@ -34,5 +40,9 @@ class SpaceResponse(SpaceBase):
 
     id: int
     is_active: bool
+    working_hours_start: int | None = None
+    working_hours_end: int | None = None
+    min_duration_minutes: int | None = None
+    max_duration_minutes: int | None = None
 
     model_config = {"from_attributes": True}