fix(api): /api/projects/:id returns 404 (not 500) for unknown id incl. superusers

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

backend/app/api_deployment.py

@@ -10,7 +10,7 @@ from __future__ import annotations
 import json
 from typing import Any
 
-from fastapi import APIRouter, Request
+from fastapi import APIRouter, HTTPException, Request
 
 from . import auth, db
 
@@ -53,7 +53,7 @@ def make_router() -> APIRouter:
             (project_id,),
         ).fetchone()
         if row is None:
-            auth.require_project_readable(viewer, project_id)  # raises 404
+            raise HTTPException(status_code=404, detail="Not found")
         cfg = json.loads(row["config_json"] or "{}")
         dep = db.conn().execute("SELECT tagline FROM deployment WHERE id = 1").fetchone()
         return {