feat: usage quota visualization in AI settings

No user-facing view of AI-call/recipe/storage usage existed — only an
admin-only per-user panel. Adds the same numbers, with progress bars
against the user's actual tier limits (read fresh from the DB, not
the cached session), to Settings > AI.

v0.40.0

apps/web/messages/en.json

@@ -325,6 +325,14 @@
     "nutrition": "Nutrition",
     "apiKeys": "API Keys",
     "webhooks": "Webhooks",
+    "usage": {
+      "title": "Usage this month",
+      "description": "Resets at the start of each month ({month}).",
+      "aiCalls": "AI calls",
+      "recipes": "Recipes created",
+      "storage": "Storage",
+      "unlimited": "Unlimited"
+    },
     "byok": {
       "title": "Your API Keys (BYOK)",
       "description": "Use your own API keys instead of the app's shared quota. Keys are encrypted at rest."