fix: address code review findings

- Add retry (2 attempts) on CivitAI 429 rate limit instead of silently skipping
- Use check_same_thread=False for SQLite connection (aiohttp context)
- Add debug logging to silent exception handlers in proxy

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

stats_service.py

@@ -72,25 +72,28 @@ class StatsFetchService:
             )
         return self._session
 
-    async def _fetch_model(self, model_id: int) -> dict | None:
+    async def _fetch_model(self, model_id: int, _retries: int = 2) -> dict | None:
         """Fetch a single model's data from CivitAI API."""
         url = f"{_CIVITAI_API}/models/{model_id}"
         session = await self._get_session()
-        try:
-            async with session.get(url) as resp:
-                if resp.status == 429:
-                    logger.warning("[LM-Remote] CivitAI rate limited, backing off")
-                    await asyncio.sleep(5)
-                    return None
-                if resp.status != 200:
-                    logger.debug("[LM-Remote] CivitAI returned %d for model %d",
-                                 resp.status, model_id)
-                    return None
-                return await resp.json()
-        except Exception as exc:
-            logger.warning("[LM-Remote] CivitAI fetch failed for model %d: %s",
-                           model_id, exc)
-            return None
+        for attempt in range(_retries + 1):
+            try:
+                async with session.get(url) as resp:
+                    if resp.status == 429:
+                        logger.warning("[LM-Remote] CivitAI rate limited, backing off (attempt %d)",
+                                       attempt + 1)
+                        await asyncio.sleep(5 * (attempt + 1))
+                        continue
+                    if resp.status != 200:
+                        logger.debug("[LM-Remote] CivitAI returned %d for model %d",
+                                     resp.status, model_id)
+                        return None
+                    return await resp.json()
+            except Exception as exc:
+                logger.warning("[LM-Remote] CivitAI fetch failed for model %d: %s",
+                               model_id, exc)
+                return None
+        return None
 
     async def fetch_stats_for_models(
         self,