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/app/api/help_center/branding.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.
@@ -75,8 +75,8 @@ def domain_status_response(row: HelpCenterSettings) -> DomainStatusResponse:
             ),
             DnsRecord(
                 type="TXT",
-                host=f"_chattermate.{row.custom_domain}",
-                value=f"cm-verify={row.domain_verification_token}",
+                host=f"_replypier.{row.custom_domain}",
+                value=f"rp-verify={row.domain_verification_token}",
                 verified=row.txt_record_verified,
             ),
         ]
@@ -100,7 +100,7 @@ async def settings_response(
         .all()
     )
     response = HelpCenterSettingsResponse.model_validate(row)
-    # Absolute (api-origin) URL: the admin runs on app.chattermate.chat, whose
+    # Absolute (api-origin) URL: the admin runs on app.replypier.site, whose
     # nginx serves any *.png path as a static asset — a host-relative
     # /api/v1/uploads/*.png would 404 there. Anchor to the backend origin.
     response.logo_url = (