feat: remove unused image retrieval endpoint and add human-readable time formatting filters

Co-authored-by: Copilot <copilot@github.com>

backend/app/routers/generate.py

@@ -211,31 +211,6 @@ async def get_generated_image(
     }
 
 
-@router.get("/images/{image_id}")
-async def get_generated_image(
-    image_id: str,
-    current_user: dict = Depends(get_current_user),
-) -> dict:
-    """Return details for a single generated image."""
-    user_id = current_user.get("id") or current_user.get("sub")
-    conn = get_conn()
-    row = conn.execute(
-        """SELECT id, model_id, prompt, image_data, created_at
-           FROM generated_images
-           WHERE id = ? AND user_id = ?""",
-        [image_id, user_id],
-    ).fetchone()
-    if not row:
-        raise HTTPException(status_code=404, detail="Image not found")
-    return {
-        "id": str(row[0]),
-        "model_id": row[1],
-        "prompt": row[2],
-        "image_data": row[3],
-        "created_at": row[4].isoformat() if row[4] else None,
-    }
-
-
 @router.post("/video", response_model=VideoResponse)
 async def generate_video(
     body: VideoRequest,