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/.env.e2e

@@ -4,7 +4,7 @@
 # NO_ENTERPRISE and the real DATABASE_URL are exported by stack.sh (they depend on
 # the edition and the local Postgres). This placeholder points nowhere, so a backend
 # started without stack.sh fails fast instead of falling back to the dev database.
-DATABASE_URL=postgresql+psycopg://set-by-stack-sh@127.0.0.1:1/chattermate_e2e
+DATABASE_URL=postgresql+psycopg://set-by-stack-sh@127.0.0.1:1/replypier_e2e
 
 ENVIRONMENT=test
 JWT_SECRET_KEY=e2e-jwt-secret-not-for-production
@@ -35,7 +35,7 @@ FIREBASE_CREDENTIALS=/nonexistent/firebase-config.json
 AWS_ACCESS_KEY_ID=
 AWS_SECRET_ACCESS_KEY=
 
-# Providers that ignore the org's base_url (e.g. the CHATTERMATE default model)
+# Providers that ignore the org's base_url (e.g. the REPLYPIER default model)
 # still land on the fake LLM through the openai SDK's env fallback.
 OPENAI_BASE_URL=http://127.0.0.1:14010/v1
 OPENAI_API_KEY=e2e-fake-key