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

.gitignore

@@ -25,13 +25,13 @@ uploads/
 *.csr.crt
 /shopify/
 
-# WordPress plugin source lives in its own repo (chattermate-wordpress-plugin);
+# WordPress plugin source lives in its own repo (replypier-wordpress-plugin);
 # only the built, installable zip is tracked here for manual download.
 /wordpress/*
-!/wordpress/chattermate-chat.zip
+!/wordpress/replypier-chat.zip
 
 # Firebase service account key (contains sensitive credentials)
-chattermate-13e0a-firebase-adminsdk-7dqo6-57f3de88cb.json
+*-firebase-adminsdk-*.json
 
 test.db
 *.db
@@ -71,7 +71,7 @@ config/
 frontend/.env.*.bak*
 
 # Stale loader copies — server.js serves the current build from frontend/public/webclient
-chattermate-test/chattermate.min.js
+replypier-test/replypier.min.js
 
 # Only the :dev webclient build emits a sourcemap, and the committed loader is
 # the :prod one, which does not reference it. Keeps a stray dev artifact out.