feat: phase 2 - polls, memories, notifications, stats v0.1.0

- Group polls with option/rollcall modes, edit by creator, auto-settle
- Multimedia memories with upload, preview, inline video playback
- In-app notifications for poll/team/group events
- Points system and group stats dashboard
- Group detail tabs with icons (activity/polls/memories/stats)
- Fix: nginx file upload size, static cache blocking API, timezone, auto-cancel

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/pb_migrations/1776504407_updated_poll_options.js

@@ -0,0 +1,16 @@
+/// <reference path="../pb_data/types.d.ts" />
+migrate((db) => {
+  const dao = new Dao(db)
+  const collection = dao.findCollectionByNameOrId("w30law0vgssvgxm")
+
+  collection.createRule = "@request.auth.id != \"\""
+
+  return dao.saveCollection(collection)
+}, (db) => {
+  const dao = new Dao(db)
+  const collection = dao.findCollectionByNameOrId("w30law0vgssvgxm")
+
+  collection.createRule = "@request.auth.id != \"\" && poll.creator = @request.auth.id"
+
+  return dao.saveCollection(collection)
+})