Initial commit: mumh5, a modern Mumble client

Electron desktop app with a Svelte 5 interface for any Mumble server.

- Mumble protocol core: TLS, handshake, channels, users, text, plugin data,
  client-side pacing of Murmur's rate limits
- Voice: WebCodecs Opus over the TCP tunnel, voice activity, push to talk,
  always-on, devices, per-user volume and local mute
- Several servers at once, voice on one; server rail with icons and ordering
- Chat: channels, direct messages, side chat, file sharing through f0ckm,
  inline images without it, click-to-play YouTube
- Profiles with rich descriptions, registration, rename, nicknames,
  connection information and moderation menus
- Identity wizard, multiple identities, PKCS#12 import/export, desktop
  Mumble certificate import, certificate pinning and viewer
- Tray icon with voice state
- Unit, server and end-to-end tests against a real Murmur

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

electron/certs.ts

@@ -0,0 +1,39 @@
+import { X509Certificate } from 'node:crypto';
+
+export interface CertDetails {
+  subject: string;
+  issuer: string;
+  validFrom: string;
+  validTo: string;
+  serialNumber: string;
+  fingerprint: string;     // SHA-1, the hash Mumble uses for users
+  fingerprint256: string;
+  subjectAltName: string;
+  keyType: string;
+  keyBits: number | null;
+  ca: boolean;
+  selfSigned: boolean;
+  pem: string;
+}
+
+// Plain, IPC-safe summary of a certificate for the viewer
+export function describeCert(input: string | Buffer | X509Certificate): CertDetails {
+  const c = input instanceof X509Certificate ? input : new X509Certificate(input);
+  const key = c.publicKey;
+  const d = key.asymmetricKeyDetails;
+  return {
+    subject: c.subject,
+    issuer: c.issuer,
+    validFrom: new Date(c.validFrom).toISOString(),
+    validTo: new Date(c.validTo).toISOString(),
+    serialNumber: c.serialNumber,
+    fingerprint: c.fingerprint,
+    fingerprint256: c.fingerprint256,
+    subjectAltName: c.subjectAltName ?? '',
+    keyType: key.asymmetricKeyType ?? 'unknown',
+    keyBits: d?.modulusLength ?? null,
+    ca: c.ca,
+    selfSigned: c.checkIssued(c),
+    pem: c.toString()
+  };
+}