feat: two-way sync between support tickets and Gitea issues (v0.63.0)

Outbound (already existed one-way: ticket create -> Gitea issue) now
also mirrors status changes: closing/reopening a ticket in the admin
UI closes/reopens the linked Gitea issue, and replies posted from
Epicure (by the ticket owner or an admin) post as a comment on the
issue. Captures and stores the Gitea issue number at creation time
to address these follow-up calls without re-parsing the issue URL.

Inbound: new webhook receiver at /api/webhooks/gitea, verified via
HMAC-SHA256 signature (X-Gitea-Signature) with a configurable
GITEA_WEBHOOK_SECRET site setting, deduped by delivery id the same
way the existing Stripe receiver dedupes events. Handles "issues"
(closed/reopened -> ticket status) and "issue_comment" (created ->
appends to the ticket's comment thread), skipping comments Epicura
already posted itself (matched by Gitea comment id) to avoid loops.

New support_ticket_comments table backs a lightweight conversation
thread on both the user-facing support page and the admin support
manager, each comment tagged by author (user/admin/gitea).

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "epicure",
-  "version": "0.62.0",
+  "version": "0.63.0",
   "private": true,
   "scripts": {
     "dev": "pnpm --filter web dev",