security: v2.0 — AES-GCM crypto, SSRF guards, rate limits, hardening

Breaking wire-format change: dual-read (V1+V2) / single-write (V2) so
existing user secrets, stored messages, and inter-tenant key keep
working. Old clients and relays lose cross-version chat until both
sides are upgraded.

Relay
- Switch clientEncrypt/masterEncrypt to AES-256-GCM with HKDF-derived
  per-ciphertext salts; keep CBC-V1 fallback on decrypt only.
- On-bootstrap migration re-envelopes tenant secret_encrypted and the
  inter-tenant key to GCM-V2 (idempotent).
- CORS: stop reflecting arbitrary Origin; allow own origin + optional
  RELAY_CORS_ORIGINS env allowlist; drop Access-Control-Allow-Credentials.
- Generic error messages replace "no such user: <name>" enumeration.
- Exception messages no longer echoed back; logged server-side.
- Collab-lock max hold capped at 10min so a member can't grief-refresh
  forever.
- Attachment filenames validated against hex.<ext> pattern.
- Passwords min length 10; /api/account/password rate-limited.

App / Electron client
- Shared hyprcrdRelayEncrypt/Decrypt helpers (GCM-V2 write, V1 read).
- Chat + collab-buckets plugins delegate to the shared helpers.
- Poll + push + attachments migrated to the dual-format path.
- /api/relay/settings GET returns has_key boolean; secret never echoed.
- Setup endpoint now CSRF-checked.
- SSRF: CURLOPT_PROTOCOLS restricted to HTTP(S) everywhere; bookmarks
  favicon fetch also blocks private/loopback/link-local.
- Login / password-change rate limiter moved to DB-backed IP keying.
- Passwords min length 10 throughout.
- Zip import enforces per-file (25MB) and total (500MB) caps, extension
  allowlist, no-overwrite.
- Verbose relay-push debug gated behind APP_DEBUG env.

Version bumped to 2.0.0 (protocol-breaking).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

relay/ui/app.js

@@ -199,7 +199,7 @@ async function doChangePassword() {
     const err = $('cp-err');
     err.textContent = '';
     if (!current || !newPw) { err.textContent = 'all fields required'; return; }
-    if (newPw.length < 4) { err.textContent = 'new password too short'; return; }
+    if (newPw.length < 10) { err.textContent = 'new password must be at least 10 chars'; return; }
     if (newPw !== newPw2) { err.textContent = 'new passwords don\'t match'; return; }
     if (current === newPw) { err.textContent = 'new password must differ from current'; return; }
 
@@ -231,7 +231,7 @@ async function doSetup() {
     const err = $('setup-err');
     err.textContent = '';
     if (!username) { err.textContent = 'username required'; return; }
-    if (password.length < 4) { err.textContent = 'password too short'; return; }
+    if (password.length < 10) { err.textContent = 'password must be at least 10 chars'; return; }
     if (superSecret.length < 12) { err.textContent = 'super-shared secret needs at least 12 chars'; return; }
     const res = await api('api/setup', { method: 'POST', body: { username, password, super_secret: superSecret } });
     if (res.ok) {
@@ -1039,8 +1039,8 @@ async function createUser() {
 }
 
 async function resetUserPassword(id, username) {
-    const newPw = prompt(`new password for ${username} (min 4 chars):`);
-    if (!newPw || newPw.length < 4) { toast('password too short', true); return; }
+    const newPw = prompt(`new password for ${username} (min 10 chars):`);
+    if (!newPw || newPw.length < 10) { toast('password too short', true); return; }
     const res = await api('api/users/' + id, { method: 'PATCH', body: { password: newPw } });
     if (res.ok) toast('password updated');
     else toast(res.error || 'failed', true);