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):

server/services/recipe_service.py

@@ -147,6 +147,22 @@ async def create_recipe(
     db.add(version)
     await db.flush()
 
+    # Create initial task with technical drawing if file was uploaded
+    if data.file_path:
+        initial_task = RecipeTask(
+            version_id=version.id,
+            order_index=0,
+            title="Technical Drawing",
+            file_path=data.file_path,
+            file_type=data.file_type or (
+                "pdf" if data.file_path.lower().endswith(".pdf")
+                else "image"
+            ),
+            annotations_json=data.annotations_json,
+        )
+        db.add(initial_task)
+        await db.flush()
+
     await _write_audit(
         db,
         recipe_id=recipe.id,
@@ -223,6 +239,46 @@ async def create_new_version(
     # Deep-copy tasks + subtasks
     await _copy_tasks_to_version(db, source_version=current, target_version=new_version)
 
+    # Apply task-level updates (file_path, annotations_json) to the first task
+    if data.file_path is not None or data.annotations_json is not None:
+        # Reload new version's tasks
+        result_tasks = await db.execute(
+            select(RecipeTask)
+            .where(RecipeTask.version_id == new_version.id)
+            .order_by(RecipeTask.order_index)
+        )
+        tasks = list(result_tasks.scalars().all())
+
+        if tasks:
+            first_task = tasks[0]
+            if data.file_path is not None:
+                first_task.file_path = data.file_path
+                # Auto-detect file_type from extension
+                if data.file_type:
+                    first_task.file_type = data.file_type
+                elif data.file_path.lower().endswith(".pdf"):
+                    first_task.file_type = "pdf"
+                else:
+                    first_task.file_type = "image"
+            if data.annotations_json is not None:
+                first_task.annotations_json = data.annotations_json
+        else:
+            # No tasks yet — create a default task to hold the drawing
+            default_task = RecipeTask(
+                version_id=new_version.id,
+                order_index=0,
+                title="Technical Drawing",
+                file_path=data.file_path,
+                file_type=data.file_type or (
+                    "pdf" if data.file_path and data.file_path.lower().endswith(".pdf")
+                    else "image"
+                ),
+                annotations_json=data.annotations_json,
+            )
+            db.add(default_task)
+
+        await db.flush()
+
     # Apply header updates
     update_fields: dict = {}
     if data.name is not None: