feat: per-position camera settings, material alias dialog, product delete, media browser links

- Per-render-position focal_length_mm/sensor_width_mm (DB → pipeline → Blender)
- FOV-based camera distance with min clamp fix for wide-angle lenses
- Unmapped materials blocking dialog on "Dispatch Renders" with batch alias creation
- Material check endpoint (GET /orders/{id}/check-materials)
- Batch alias endpoint (POST /materials/batch-aliases)
- Quick-map "No alias" badges on Materials page
- Full product hard-delete with storage cleanup (MinIO + disk files + orphaned CadFile)
- Delete button on ProductDetail page with confirmation
- Clickable product names in Media Browser (links to product page)
- Single-line render dispatch/retry (POST /orders/{id}/lines/{id}/dispatch-render)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/routers/render_templates.py

@@ -116,9 +116,11 @@ async def list_render_templates(
 @router.post("/render-templates", response_model=RenderTemplateOut, status_code=status.HTTP_201_CREATED)
 async def create_render_template(
     name: str = Form(...),
-    file: UploadFile = File(...),
+    file: UploadFile | None = File(None),
+    clone_blend_from: str | None = Form(None),
     category_key: str | None = Form(None),
     output_type_id: str | None = Form(None),
+    output_type_ids: str | None = Form(None),
     target_collection: str = Form("Product"),
     material_replace_enabled: bool = Form(False),
     lighting_only: bool = Form(False),
@@ -127,30 +129,54 @@ async def create_render_template(
     user: User = Depends(require_admin_or_pm),
     db: AsyncSession = Depends(get_db),
 ):
-    if not file.filename or not file.filename.endswith(".blend"):
-        raise HTTPException(400, detail="File must be a .blend file")
-
     # Normalise empty strings from form data to None
     if category_key == "" or category_key == "null":
         category_key = None
     if output_type_id == "" or output_type_id == "null":
         output_type_id = None
+    if clone_blend_from == "" or clone_blend_from == "null":
+        clone_blend_from = None
 
     template_id = uuid.uuid4()
     blend_path = _blend_dir() / f"{template_id}.blend"
 
-    with open(blend_path, "wb") as f:
-        shutil.copyfileobj(file.file, f)
+    if file and file.filename:
+        if not file.filename.endswith(".blend"):
+            raise HTTPException(400, detail="File must be a .blend file")
+        with open(blend_path, "wb") as f:
+            shutil.copyfileobj(file.file, f)
+        original_filename = file.filename
+        final_blend_path = str(blend_path)
+    elif clone_blend_from:
+        # Share the same .blend file (no copy — just reference the same path)
+        source = await db.execute(
+            select(RenderTemplate).where(RenderTemplate.id == uuid.UUID(clone_blend_from))
+        )
+        source_tmpl = source.unique().scalar_one_or_none()
+        if not source_tmpl:
+            raise HTTPException(404, detail="Source template not found")
+        source_path = Path(source_tmpl.blend_file_path)
+        if not source_path.exists():
+            raise HTTPException(404, detail="Source .blend file not found on disk")
+        final_blend_path = source_tmpl.blend_file_path
+        original_filename = source_tmpl.original_filename
+    else:
+        raise HTTPException(400, detail="Provide either a .blend file or clone_blend_from template ID")
 
     ot_uuid = uuid.UUID(output_type_id) if output_type_id else None
 
+    # Parse M2M output_type_ids (comma-separated string from FormData)
+    m2m_ot_ids: list[str] = []
+    if output_type_ids and output_type_ids.strip():
+        m2m_ot_ids = [s.strip() for s in output_type_ids.split(",") if s.strip()]
+
     tmpl = RenderTemplate(
         id=template_id,
         name=name,
         category_key=category_key,
         output_type_id=ot_uuid,
-        blend_file_path=str(blend_path),
-        original_filename=file.filename,
+        blend_file_path=final_blend_path,
+        original_filename=original_filename,
         target_collection=target_collection,
         material_replace_enabled=material_replace_enabled,
         lighting_only=lighting_only,
@@ -160,12 +186,13 @@ async def create_render_template(
     db.add(tmpl)
     await db.flush()
 
-    # Sync M2M from initial output_type_id
-    if ot_uuid:
-        from app.domains.rendering.models import render_template_output_types
+    # Sync M2M output types
+    from app.domains.rendering.models import render_template_output_types
+    ot_ids_to_link = m2m_ot_ids if m2m_ot_ids else ([str(ot_uuid)] if ot_uuid else [])
+    for ot_id_str in ot_ids_to_link:
         await db.execute(
             render_template_output_types.insert().values(
-                template_id=template_id, output_type_id=ot_uuid,
+                template_id=template_id, output_type_id=uuid.UUID(ot_id_str),
             )
         )
 
@@ -250,9 +277,15 @@ async def delete_render_template(
     if not tmpl:
         raise HTTPException(404, detail="Render template not found")
 
-    # Delete .blend file
+    # Only delete .blend file if no other template shares it
     blend_path = Path(tmpl.blend_file_path)
-    if blend_path.exists():
+    other_refs = await db.execute(
+        select(RenderTemplate.id).where(
+            RenderTemplate.blend_file_path == tmpl.blend_file_path,
+            RenderTemplate.id != template_id,
+        )
+    )
+    if not other_refs.first() and blend_path.exists():
         blend_path.unlink(missing_ok=True)
 
     await db.execute(sql_delete(RenderTemplate).where(RenderTemplate.id == template_id))
@@ -277,10 +310,17 @@ async def upload_blend_file(
 
     blend_path = _blend_dir() / f"{template_id}.blend"
 
-    # Remove old file if path changed
+    # Only remove old file if no other template shares it
     old_path = Path(tmpl.blend_file_path)
     if old_path.exists() and old_path != blend_path:
-        old_path.unlink(missing_ok=True)
+        other_refs = await db.execute(
+            select(RenderTemplate.id).where(
+                RenderTemplate.blend_file_path == tmpl.blend_file_path,
+                RenderTemplate.id != template_id,
+            )
+        )
+        if not other_refs.first():
+            old_path.unlink(missing_ok=True)
 
     with open(blend_path, "wb") as f:
         shutil.copyfileobj(file.file, f)