docs: initial project setup - Asterisk 20 + FreePBX 17 PBX

Phase 1 installation completed (8/10 tasks):
- Ubuntu 24.04, Asterisk 20.18.2 compiled from source
- FreePBX 17.0.25 with PJSIP extensions (1001, 1002)
- MariaDB 10.11.14, Apache 2.4, PHP 8.3
- nftables firewall and Fail2ban security configured

Pending: softphone testing, IVR/queues config, Phase 2 (PSTN trunks)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,20 @@
+# Secrets
+.db_password
+*.secret
+*.key
+*.pem
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Logs (keep structure, ignore content)
+logs/*.log
+!logs/.gitkeep
+
+# Editor
+*.swp
+*.swo
+*~
+.vscode/
+.idea/