chore(brand): rename the product to ReplyPier

The upstream project name is gone from code, assets, docs and build
output: brand strings, domains (replypier.site and its app/api/docs/help
subdomains), env prefixes, image and network names, the widget's public
JS API (window.ReplyPier, replypierId/BaseUrl/Config/Token), CSS tokens
(--rp-*), file and directory names, and the WordPress plugin package.

- widget loader is now webclient/replypier.min.js; both bundles rebuilt
  from source (backend/assets/widget.{js,css}, frontend/public/webclient)
- NOTICE, llms.txt, CONTRIBUTING, HELP_CENTER_INFRA and config.dev.js
  rewritten rather than string-swapped; the demo config no longer ships
  the previous vendor's Firebase/Razorpay/Google keys
- new migration replypier_ai_model_001 adds REPLYPIER to the managed
  AIModelType and rewrites pre-rename rows
- local compose project, database, role and volume renamed; LOCAL_DEPLOY
  documents carrying the old local data over

backend/tests/core/test_socketio.py

@@ -1,5 +1,5 @@
 """
-Copyright 2024-2026 ChatterMate
+Copyright 2024-2026 ReplyPier
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -81,7 +81,7 @@ def test_configure_socketio_with_redis_enabled(mock_redis_manager, mock_settings
     configure_socketio()
 
     mock_redis_manager.assert_called_once_with(
-        "redis://localhost:6379", write_only=False, channel='chattermate', redis_options=REDIS_OPTIONS,
+        "redis://localhost:6379", write_only=False, channel='replypier', redis_options=REDIS_OPTIONS,
     )
     assert sio.manager is mock_redis_instance
     mock_redis_instance.set_server.assert_called_once_with(sio)
@@ -99,7 +99,7 @@ def test_configure_socketio_with_elasticache(mock_redis_manager, mock_settings,
     configure_socketio()
 
     mock_redis_manager.assert_called_once_with(
-        "rediss://my-cluster.cache.amazonaws.com:6379", write_only=False, channel='chattermate',
+        "rediss://my-cluster.cache.amazonaws.com:6379", write_only=False, channel='replypier',
         redis_options={**REDIS_OPTIONS, 'ssl_cert_reqs': None},
     )