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/scripts/upgrade-check.sh

@@ -13,8 +13,8 @@ set -euo pipefail
 E2E_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 REPO_DIR="$(cd "$E2E_DIR/.." && pwd)"
 PG_URL="${E2E_PG_URL:-postgresql://${USER}@127.0.0.1:5432}"; PG_URL="${PG_URL%/}"
-DB_NAME="chattermate_upgrade_e2e"
-FRESH_DB="chattermate_fresh_e2e"
+DB_NAME="replypier_upgrade_e2e"
+FRESH_DB="replypier_fresh_e2e"
 BASE_REF="${1:-$(git -C "$REPO_DIR" describe --tags --abbrev=0 --match 'v*')}"
 if [[ -z "${E2E_PYTHON:-}" ]]; then
   if [[ -x "$REPO_DIR/backend/venv/bin/python" ]]; then E2E_PYTHON="$REPO_DIR/backend/venv/bin/python"; else E2E_PYTHON="python3"; fi