docs: document full API surface in OpenAPI spec (v0.26.0)

Went from 14 to ~100 documented endpoints in lib/openapi.ts — pantry,
meal-plans, shopping-lists, collections, users/social, ai/*, webhooks,
conversations, notifications, and admin routes now all appear in
/docs with accurate request/response schemas. No auth/route changes.

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "epicure",
-  "version": "0.25.1",
+  "version": "0.26.0",
   "private": true,
   "scripts": {
     "dev": "pnpm --filter web dev",