fix: code review — security fixes, dedup, cleanup

- setup: validate roles against users.VALID_ROLES (Supervisor was missing)
- files: fix path traversal prefix-match edge case (is_relative_to),
  dedupe path validation into resolve_upload_path(), use logging not print
- measurements: extract shared _build_measurement_filters() helper
- client app: prevent open redirect via Referer on /set-language
- maker: guard resp.json() in parse-technical-sheet proxy
- measure/maker: extract shared file proxy into services/file_proxy.py
- measure: localize supervisor validation error messages
- annotation-editor: remove global keydown listener in destroy()

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/backend/api/routers/files.py

@@ -1,5 +1,5 @@
 """File upload/download/delete router for images and PDFs."""
-import os
+import logging
 import re
 from pathlib import Path
 
@@ -11,6 +11,8 @@ from src.backend.config import settings
 from src.backend.api.middleware.api_key import get_current_user, require_maker
 from src.backend.models.orm.user import User
 
+logger = logging.getLogger(__name__)
+
 router = APIRouter(prefix="/api/files", tags=["files"])
 
 # Allowed MIME types
@@ -65,6 +67,37 @@ def sanitize_filename(filename: str) -> str:
     return filename
 
 
+def resolve_upload_path(file_path: str) -> Path:
+    """Resolve a user-supplied relative path inside the uploads directory.
+
+    Raises:
+        HTTPException: 404 if the path escapes the uploads directory,
+            cannot be resolved, or does not point to an existing file.
+    """
+    try:
+        full_path = (settings.upload_path / file_path).resolve()
+        if not full_path.is_relative_to(settings.upload_path.resolve()):
+            raise HTTPException(
+                status_code=status.HTTP_403_FORBIDDEN,
+                detail="Access denied",
+            )
+    except HTTPException:
+        raise
+    except (OSError, RuntimeError, ValueError):
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="File not found",
+        )
+
+    if not full_path.exists() or not full_path.is_file():
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="File not found",
+        )
+
+    return full_path
+
+
 def generate_thumbnail(image_path: Path, thumbnail_path: Path, max_size: tuple[int, int] = (200, 200)):
     """Generate a thumbnail for an image."""
     try:
@@ -73,7 +106,7 @@ def generate_thumbnail(image_path: Path, thumbnail_path: Path, max_size: tuple[i
             img.save(thumbnail_path, quality=85)
     except Exception as e:
         # If thumbnail generation fails, we continue without it
-        print(f"Thumbnail generation failed: {e}")
+        logger.warning("Thumbnail generation failed for %s: %s", image_path, e)
 
 
 @router.post("/upload")
@@ -164,30 +197,7 @@ async def get_file(
 
     Requires authentication but no specific role.
     """
-    # Construct full path
-    full_path = settings.upload_path / file_path
-
-    # Security: ensure path is within uploads directory
-    try:
-        full_path = full_path.resolve()
-        if not str(full_path).startswith(str(settings.upload_path.resolve())):
-            raise HTTPException(
-                status_code=status.HTTP_403_FORBIDDEN,
-                detail="Access denied",
-            )
-    except Exception:
-        raise HTTPException(
-            status_code=status.HTTP_404_NOT_FOUND,
-            detail="File not found",
-        )
-
-    # Check if file exists
-    if not full_path.exists() or not full_path.is_file():
-        raise HTTPException(
-            status_code=status.HTTP_404_NOT_FOUND,
-            detail="File not found",
-        )
-
+    full_path = resolve_upload_path(file_path)
     return FileResponse(full_path)
 
 
@@ -200,29 +210,7 @@ async def delete_file(
 
     Also deletes associated thumbnail if it exists.
     """
-    # Construct full path
-    full_path = settings.upload_path / file_path
-
-    # Security: ensure path is within uploads directory
-    try:
-        full_path = full_path.resolve()
-        if not str(full_path).startswith(str(settings.upload_path.resolve())):
-            raise HTTPException(
-                status_code=status.HTTP_403_FORBIDDEN,
-                detail="Access denied",
-            )
-    except Exception:
-        raise HTTPException(
-            status_code=status.HTTP_404_NOT_FOUND,
-            detail="File not found",
-        )
-
-    # Check if file exists
-    if not full_path.exists() or not full_path.is_file():
-        raise HTTPException(
-            status_code=status.HTTP_404_NOT_FOUND,
-            detail="File not found",
-        )
+    full_path = resolve_upload_path(file_path)
 
     # Delete thumbnail if it exists
     if full_path.parent.name != "thumbnails":