feat: add close confirmation modal with minimize to tray option

Implemented a confirmation modal when users try to close the application:
- Modal always shows with three options: Cancel, Minimize to Tray, Close Application
- Detects if Claude is actively running and shows appropriate warning message
- Removed minimize_to_tray config setting (no longer needed)
- Added core:window:allow-hide permission for window hiding
- Created CloseAppConfirmModal component with keyboard shortcuts (Escape to cancel)
- Added close_application command to properly exit the app
- Backend emits window-close-requested event for frontend to handle

This provides better UX by giving users clear choices every time they close,
preventing accidental closures during active work sessions.

src-tauri/src/tray.rs

@@ -4,8 +4,6 @@ use tauri::{
     AppHandle, Manager,
 };
 
-use crate::config::HikariConfig;
-
 pub fn setup_tray(app: &AppHandle) -> tauri::Result<()> {
     let show_item = MenuItem::with_id(app, "show", "Show Hikari", true, None::<&str>)?;
     let quit_item = MenuItem::with_id(app, "quit", "Quit", true, None::<&str>)?;
@@ -48,21 +46,3 @@ pub fn setup_tray(app: &AppHandle) -> tauri::Result<()> {
 
     Ok(())
 }
-
-pub fn should_minimize_to_tray(app: &AppHandle) -> bool {
-    let config_path = app
-        .path()
-        .app_config_dir()
-        .ok()
-        .map(|p| p.join("hikari-config.json"));
-
-    if let Some(path) = config_path {
-        if let Ok(content) = std::fs::read_to_string(&path) {
-            if let Ok(config) = serde_json::from_str::<HikariConfig>(&content) {
-                return config.minimize_to_tray;
-            }
-        }
-    }
-
-    false
-}