Initial build: Asterisk voicemail transcription + portal

- mailcmd replacement (vm_mailcmd.py): faster-whisper transcription (CPU int8),
  extractive summary + intent tags + spoken-digit number extraction,
  multipart/alternative HTML email, fail-safe relay of original message
- Telegram DM delivery (vm_telegram.py) with per-mailbox routing
- Caller-ID -> name (vm_contacts.py): file / google / carddav backends
- SQLite store (vm_store.py) with content-addressed audio
- FastAPI portal (vm_web.py): PIN login, list/play/delete, per-user settings,
  zero JS, loopback-only behind Apache TLS
- Backfill importer (vm_import.py) for existing spool recordings
- systemd unit, Apache vhost + certbot TLS, install.sh
- Docs: INSTALL, CONFIGURATION, ARCHITECTURE, OPERATIONS, SECURITY, TESTING

Verified end-to-end on mail.txt3.net: 157 historical messages backfilled,
live voicemail -> transcribed -> stored -> visible at https://vm.txt3.net.

apache/vm.txt3.net-step1.conf

@@ -0,0 +1,12 @@
+<VirtualHost 51.68.212.39:80 [2001:41d0:801:2000::2245]:80>
+    ServerName vm.txt3.net
+    DocumentRoot /home/txt3/domains/vm.txt3.net/public_html
+    ErrorLog /var/log/virtualmin/vm.txt3.net_error_log
+    CustomLog /var/log/virtualmin/vm.txt3.net_access_log combined
+
+    <Directory /home/txt3/domains/vm.txt3.net/public_html>
+        Require all granted
+        Options -Indexes
+        AllowOverride None
+    </Directory>
+</VirtualHost>