fix: Admin Insights page could crash on a single query failure (v0.55.2)

Two changes:
1. Replaced positional `GROUP BY 1` (not used anywhere else in this
   codebase) with the conventional pattern of repeating the actual
   grouped expression — matches every other groupBy call site in the app.
2. Switched Promise.all -> Promise.allSettled across the six independent
   aggregate queries feeding the six charts, defaulting a failed one to
   an empty array (that chart just renders "No data yet") instead of
   taking the whole page down. Logs the failure server-side either way.

Couldn't reproduce locally (no DB in this sandbox), but confirmed the
allSettled path works: the production build itself hit a real connection
failure against the (absent) local DB and degraded cleanly instead of
crashing, which is exactly the resilience this fixes.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "epicure",
-  "version": "0.55.1",
+  "version": "0.55.2",
   "private": true,
   "scripts": {
     "dev": "pnpm --filter web dev",