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

deploy/local/init_env.py

@@ -26,7 +26,7 @@ def main() -> None:
     password = compose_env.read_text().strip().split("=", 1)[1]
     fernet_key = base64.b64encode(base64.urlsafe_b64encode(secrets.token_bytes(32))).decode()
     settings = {
-        "DATABASE_URL": f"postgresql+psycopg://chattermate:{password}@127.0.0.1:15432/chattermate",
+        "DATABASE_URL": f"postgresql+psycopg://replypier:{password}@127.0.0.1:15432/replypier",
         "REDIS_ENABLED": "true",
         "REDIS_URL": "redis://127.0.0.1:16380/0",
         "ENVIRONMENT": "production",