chore: settle product naming across app, widget and deployments

One word everywhere: ReplyPier in UI copy, package and image names, the
replypier.site domains (app/api/docs/help), REPLYPIER_* settings and the
--rp-* design tokens.

- public widget API is window.ReplyPier with replypierId / replypierBaseUrl /
  replypierConfig / replypierToken, loader at webclient/replypier.min.js;
  both bundles rebuilt from source
- NOTICE, llms.txt, CONTRIBUTING, HELP_CENTER_INFRA and the demo runtime
  config rewritten; the demo config ships no third-party keys
- migration adds the ReplyPier managed model value to the AI model enum
- local compose project, database, role, volume and Docker network carry the
  same name

backend/app/services/ticket_jira.py

@@ -1,5 +1,5 @@
 """
-Copyright 2024-2026 ChatterMate
+Copyright 2024-2026 ReplyPier
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -15,7 +15,7 @@ limitations under the License.
 
 One-way Jira escalation for native tickets: when enabled, tickets at or
 above the configured priority get a mirrored Jira issue (external_ref_*).
-Native ChatterMate stays the source of truth — nothing syncs back.
+Native ReplyPier stays the source of truth — nothing syncs back.
 """
 
 from typing import Optional
@@ -94,7 +94,7 @@ async def maybe_escalate_to_jira(db, service, ticket: Ticket, settings_row) -> b
         from app.services.jira import JiraService
 
         description_parts = [
-            f"Escalated from ChatterMate ticket {ticket.display_number} "
+            f"Escalated from ReplyPier ticket {ticket.display_number} "
             f"(priority: {ticket.priority}, severity: {ticket.severity or 'n/a'}).",
         ]
         if ticket.ai_summary: