fix: file display, persistence, PDF support and save error handling

- Add file proxy route in maker blueprint (X-API-Key auth for browser requests)
- Persist file_path/annotations_json to DB via RecipeCreate/RecipeUpdate schemas
- Fix canvas sizing using grandparent container instead of Fabric.js wrapper div
- Defer canvas init with requestAnimationFrame for x-show timing
- Add PDF.js support in annotation-editor and annotation-viewer
- Fix annotations_json double-serialization (parse string to object before send)
- Handle FastAPI 422 validation error arrays in api_client and JS error display
- Update template URLs to use /maker/api/files/ proxy path

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/schemas/recipe.py

@@ -13,6 +13,10 @@ class RecipeCreate(BaseModel):
     code: str = Field(..., min_length=1, max_length=100)
     name: str = Field(..., min_length=1, max_length=255)
     description: Optional[str] = None
+    # Optional task-level fields for the initial technical drawing
+    file_path: Optional[str] = Field(None, max_length=500)
+    file_type: Optional[str] = Field(None, pattern="^(image|pdf)$")
+    annotations_json: Optional[dict] = None
 
 
 class RecipeUpdate(BaseModel):
@@ -20,6 +24,10 @@ class RecipeUpdate(BaseModel):
     name: Optional[str] = Field(None, min_length=1, max_length=255)
     description: Optional[str] = None
     change_notes: Optional[str] = None
+    # Task-level fields: saved to the first task of the new version
+    file_path: Optional[str] = Field(None, max_length=500)
+    file_type: Optional[str] = Field(None, pattern="^(image|pdf)$")
+    annotations_json: Optional[dict] = None
 
 
 class RecipeVersionResponse(BaseModel):