feat: system service management (gyandoot service install|remove|status)

- Create systemd + launchd service templates in resources/
- Add gyandoot-core/src/service.rs module with full lifecycle
  - systemd: user service, daemon-reload, enable, start, stop, disable
  - launchd: macOS plist, load/unload, start/stop (launchctl)
- Add 'gyandoot service install|remove|status' CLI subcommand
- Update setup wizard: prompts 'Install system service? [y/N]'
- Update install.sh: prompts user for service install after binary
- Browser auto-starts at runtime (browser_manager), no separate service needed
- Camoufox installed via npm, auto-started by GyanDoot agent loop

crates/gyandoot-tui/src/setup.rs

@@ -333,6 +333,40 @@ pub fn run_setup_wizard() -> anyhow::Result<Option<WizardResult>> {
         &format!("Configuration saved to {}", config_path.display()),
     );
 
+    // Step 7: Optional service install
+    println!();
+    terminal::section_header("System Service");
+    println!("  GyanDoot can run as a system service and auto-start on boot.");
+    println!("  This keeps the gateway server running in the background.");
+    let install_service = terminal::confirm_prompt(
+        "Install GyanDoot system service (auto-start on boot)?",
+        Some(false),
+    );
+
+    if install_service {
+        terminal::show_status(
+            terminal::StatusKind::Info,
+            "Installing system service...",
+        );
+        match gyandoot_core::service::install_service() {
+            Ok(status) => {
+                terminal::show_status(
+                    terminal::StatusKind::Success,
+                    &format!("Service installed! (init: {})", status.init_system),
+                );
+            }
+            Err(e) => {
+                terminal::show_status(
+                    terminal::StatusKind::Warning,
+                    &format!("Could not install service: {}", e),
+                );
+                println!("  You can install later with: gyandoot service install");
+            }
+        }
+    } else {
+        println!("  You can install later with: gyandoot service install");
+    }
+
     Ok(Some(WizardResult {
         provider: choice,
         config,