Wallet-verified member messaging (matrix-lines permissions, admin visibility)

- messages.js: challenge/personal_sign/recover auth (vendored pinned
  js-sha3 0.9.3 + noble-secp256k1 1.7.1, server-side only; self-tested
  positive + tamper cases), 30d HttpOnly sessions, message store on the
  volume, matrix-line permissions (your downline direct or broadcast, your
  upline chain - nothing else, so spam is impossible by construction),
  daily rate limits (30 direct / 3 broadcasts), 1500-char plain text
- chain.js: memberIdByAccount (wallet -> position for sign-in)
- API: msg-challenge/-verify/-me/-inbox/-send/-read public + msg-unread
  (count only, no auth) + admin/messages (full visibility, disclosed to
  members in the UI)
- Dashboard: Messages card with unread bell, one-tap wallet sign-in,
  inbox with auto-read, compose with to-ID or whole-team broadcast
- Admin: Member Messages review table
- Chatbot canned answer + AI system prompt updated

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

public/chat.js

@@ -48,8 +48,8 @@
      a:()=>`Two ways money reaches your position — the full diagram is at <a href="/how-pay-works">rmcircle.team/how-pay-works</a>. <strong>(1) Entry rewards:</strong> when a direct joins under your link you get their entry reward (about 326 POL at Premium) and you keep it — on every direct you bring. <strong>(2) Upgrade payments:</strong> each person below you pays you once, at the ONE level that matches how far below you they sit — someone 1 layer below pays you when they hit Ascensus, 2 layers below pays you at Fabrica, 3 at Culmen, and so on. To catch each, you must be at that level yourself and qualified, so stay one level ahead of your team. No income is guaranteed.`},
     {k:['tier','standard','premium tier','standard tier','premium vs standard','which tier','half','smaller payment','less than expected','why is my payment'],
      a:()=>`There are two tiers. <strong>Premium</strong> is what our whole team builds at (${pol()} POL entry) — full payments. <strong>Standard</strong> costs about half and pays/earns half at every level. So if a payment ever comes in smaller than expected, it usually came from a Standard-tier position below you. Your tier is <strong>set when you join and can't be changed later</strong> (upgrading advances your level, not your tier), so always join <strong>Premium</strong> and make sure the people you bring on do too. Full breakdown: <a href="/how-pay-works">how-pay-works</a>.`},
-    {k:['dashboard','my dashboard','my page','my position','my team','check my','see my','pipeline','my stats','alerts','notify me','email me','get notified'],
-     a:()=>`Your <strong>Member Dashboard</strong> is at <a href="/my">rmcircle.team/my</a> — enter your ID to see your position, your team (with a depth summary showing members per generation), your payments, your pipeline (money forming below you), any spillover under you, and a <strong>Coach Your Team</strong> panel that tells you exactly who in your leg needs a nudge and what to say. You can also turn on <strong>email alerts</strong> there to be notified the moment you're paid or need to upgrade. To share, use your personal invite page: <strong>rmcircle.team/join/&lt;your ID&gt;</strong>.`},
+    {k:['dashboard','my dashboard','my page','my position','my team','check my','see my','pipeline','my stats','alerts','notify me','email me','get notified','message','messages','contact my sponsor','contact my upline','contact my downline','reach my team'],
+     a:()=>`Your <strong>Member Dashboard</strong> is at <a href="/my">rmcircle.team/my</a> — enter your ID to see your position, your team (with a depth summary showing members per generation), your payments, your pipeline (money forming below you), any spillover under you, and a <strong>Coach Your Team</strong> panel that tells you exactly who in your leg needs a nudge and what to say. You can also turn on <strong>email alerts</strong> there, and use <strong>Messages</strong> — wallet-verified messaging with your upline and your team (sign in once with your wallet; no email needed; only people on your matrix lines can message you). To share, use your personal invite page: <strong>rmcircle.team/join/&lt;your ID&gt;</strong>.`},
     {k:['level','levels','upgrade','scintilla','ascensus','fabrica','culmen','apex','fastigium','vertex','corona','8 levels'],
      a:()=>`There are 8 Premium levels: <strong>Scintilla, Ascensus, Fabrica, Culmen, Apex, Fastigium, Vertex, Corona</strong>. Everyone starts at Scintilla. Upgrade as quickly as practical — ideally using earned POL — because the first two payments at each level are designed to help fund your next upgrade. Stay aware of your active downline's levels so you don't fall behind.`},
     {k:['30 positions','goal','milestone','matrix','how many people','team size'],