Add custom service log file support with L key

- Add ServiceLogConfig structure for per-host service log paths
- Implement L key handler for custom log file viewing via tmux popup
- Update dashboard config to support service_logs HashMap
- Add tail -f command execution over SSH for real-time log streaming
- Update status line to show L: Custom shortcut
- Document configuration format in CLAUDE.md

Each service can now have custom log file paths configured per host,
accessible via L key with same tmux popup interface as journalctl.

CLAUDE.md

@@ -20,12 +20,28 @@ A high-performance Rust-based TUI dashboard for monitoring CMTEC infrastructure.
 - Persistent storage survives agent restarts
 - Automatic flag clearing when services are restarted via dashboard
 
+### Custom Service Logs
+- Configure service-specific log file paths per host in dashboard config
+- Press `L` on any service to view custom log files via `tail -f`
+- Configuration format in dashboard config:
+```toml
+[service_logs]
+hostname1 = [
+  { service_name = "nginx", log_file_path = "/var/log/nginx/access.log" },
+  { service_name = "app", log_file_path = "/var/log/myapp/app.log" }
+]
+hostname2 = [
+  { service_name = "database", log_file_path = "/var/log/postgres/postgres.log" }
+]
+```
+
 ### Service Management
 - **Direct Control**: Arrow keys (↑↓) or vim keys (j/k) navigate services
 - **Service Actions**: 
   - `s` - Start service (sends UserStart command)
   - `S` - Stop service (sends UserStop command)
   - `J` - Show service logs (journalctl in tmux popup)
+  - `L` - Show custom log files (tail -f custom paths in tmux popup)
   - `R` - Rebuild current host
 - **Visual Status**: Green ● (active), Yellow ◐ (inactive), Red ◯ (failed)
 - **Transitional Icons**: Blue arrows during operations
@@ -34,6 +50,7 @@ A high-performance Rust-based TUI dashboard for monitoring CMTEC infrastructure.
 - **Tab**: Switch between hosts
 - **↑↓ or j/k**: Select services
 - **J**: Show service logs (journalctl)
+- **L**: Show custom log files
 - **q**: Quit dashboard
 
 ## Core Architecture Principles