feat: search matches ingredients/tags, add tag filter chips to Explore

Search previously only matched title/description. Now also matches
ingredient rawName (EXISTS subquery) and tags (unnest+ILIKE) via
sequential scan — fine at current scale, flagged for a trigram/GIN
index if it gets slow. Explore also shows the 12 most-used public
tags as clickable chips that AND-filter results via a new `tags`
query param (array containment).

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "epicure",
-  "version": "0.14.0",
+  "version": "0.15.0",
   "private": true,
   "scripts": {
     "dev": "pnpm --filter web dev",