fix WhatsApp group chat support and self-message handling

Bridge: allow fromMe messages in groups, include participant field in
message queue, bind to 0.0.0.0 for network access, QR served as HTML.

Adapter: process registered group messages (route to Claude), extract
participant for user identification, fix unbound 'phone' variable.

Tested end-to-end: WhatsApp group chat with Claude working. 442 tests pass.

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

config.json

@@ -13,12 +13,17 @@
   },
   "telegram_channels": {},
   "whatsapp": {
-    "enabled": false,
+    "enabled": true,
     "bridge_url": "http://127.0.0.1:8098",
-    "owner": null,
+    "owner": "40723197939",
     "admins": []
   },
-  "whatsapp_channels": {},
+  "whatsapp_channels": {
+    "echo-test": {
+      "id": "120363424350922235@g.us",
+      "default_model": "opus"
+    }
+  },
   "heartbeat": {
     "enabled": true,
     "interval_minutes": 30