Add FCM push notifications, queue alerts, caller ID fixes, and auto-revert agent status

Server-side:
- Add push credential auto-creation for FCM incoming call notifications
- Add queue alert FCM notifications (data-only for background delivery)
- Add queue alert cancellation on call accept/disconnect
- Fix caller ID to show caller's number instead of Twilio number
- Fix FCM token storage when refresh_token is null
- Add pre_call_status tracking to revert agent status 30s after call ends
- Add SSE fallback polling for mobile app connectivity

Mobile app:
- Add Android telecom permissions and phone account registration
- Add VoiceFirebaseMessagingService for incoming call push handling
- Add insistent queue alert notifications with custom sound
- Fix caller number display on active call screen
- Add caller ID selection dropdown on dashboard
- Add phone numbers endpoint and provider support
- Add unit tests for CallInfo, QueueState, and CallProvider
- Remove local.properties from tracking, add .gitignore

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -96,6 +96,33 @@ $api->update_call($customer_call_sid, ['twiml' => $twiml_xml]);
 - Options: roaming, ashburn, umatilla, dublin, frankfurt, singapore, sydney, tokyo, sao-paulo
 - Wrong edge causes immediate call failures (e.g., US calls with Sydney edge)
 
+## Mobile App SSE (Server-Sent Events)
+The mobile app uses SSE for real-time updates (queue changes, agent status). If SSE doesn't work (green dot stays red), the app automatically falls back to 5-second polling.
+
+### Apache + PHP-FPM Buffering Fix
+`mod_proxy_fcgi` buffers PHP output by default, which breaks SSE streaming. Fix by adding a config file on the server:
+
+```bash
+echo 'ProxyPassMatch "^/wp-json/twilio-mobile/v1/stream/events$" "unix:/run/php-fpm/www.sock|fcgi://localhost/home/shadowdao/public_html/index.php" flushpackets=on' > /etc/httpd/conf.d/twp-sse.conf
+httpd -t && systemctl restart httpd
+```
+
+- **`flushpackets=on`** is the key — tells Apache to flush PHP-FPM output immediately
+- This is a `ProxyPassMatch` directive — **cannot** go in `.htaccess`, must be server config
+- The PHP-FPM socket path (`/run/php-fpm/www.sock`) must match `/etc/httpd/conf.d/php.conf`
+- If the server uses nginx instead of Apache, add `X-Accel-Buffering: no` header (already in PHP code)
+- If behind HAProxy with HTTP/2, the issue is Apache→client buffering, not HTTP/2 framing
+
+### Diagnosis
+```bash
+# Check PHP-FPM proxy config
+grep -r "fcgi\|php-fpm" /etc/httpd/conf.d/
+# Check if flushpackets is configured
+grep -r "flushpackets" /etc/httpd/conf.d/
+# Test SSE endpoint (should stream data, not hang)
+curl -N -H "Authorization: Bearer TOKEN" https://phone.cloud-hosting.io/wp-json/twilio-mobile/v1/stream/events
+```
+
 ## Changelog
 See `README.md` for detailed version history. Current version: v2.8.9.