fix(api): rename 'metadata' to 'response_metadata' to avoid Pydantic conflict

The field name 'metadata' conflicts with Pydantic's internal ClassVar.
Renamed to 'response_metadata' throughout:
- Backend: RoutineSuggestion, BatchSuggestion, ShoppingSuggestionResponse
- Frontend: TypeScript types and component usages

This fixes the AttributeError when setting metadata on SQLModel instances.

skills-lock.json

@@ -0,0 +1,25 @@
+{
+  "version": 1,
+  "skills": {
+    "conventional-commit": {
+      "source": "github/awesome-copilot",
+      "sourceType": "github",
+      "computedHash": "f29c9486cede6c7b2df0cfb0a2e4aa67446552b991bcf17d1b309e903171f03d"
+    },
+    "frontend-design": {
+      "source": "anthropics/skills",
+      "sourceType": "github",
+      "computedHash": "063a0e6448123cd359ad0044cc46b0e490cc7964d45ef4bb9fd842bd2ffbca67"
+    },
+    "gemini-api-dev": {
+      "source": "google-gemini/gemini-skills",
+      "sourceType": "github",
+      "computedHash": "8ff8d320f21bff9dc980b8249743f39df11c80e07da3b2c5ab070d8ea9bdab46"
+    },
+    "svelte-code-writer": {
+      "source": "sveltejs/mcp",
+      "sourceType": "github",
+      "computedHash": "c0e2cce9855f8e312cbb0a05aef164b4659c672d7723e4e598ffa6bc94890542"
+    }
+  }
+}