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

e2e/specs/widget/js-api.spec.ts

@@ -1,7 +1,7 @@
 import { test, expect } from '@e2e'
 
 test.describe('widget JS API', () => {
-  test('the host page opens and closes the chat with window.ChatterMate @widget', async ({ widget }) => {
+  test('the host page opens and closes the chat with window.ReplyPier @widget', async ({ widget }) => {
     await widget.embed()
 
     await widget.api('open')