feat(palette): unify quick open into command palette with multi-source search

Merge file picker into command palette. Single Cmd+P entry searches
files, sessions, settings pages and commands; groups re-order by best
fuzzy score per source. Sessions show branch labels; git status is
lazily fetched for all session directories on open.

Drop QuickOpenDialog and Cmd+K shortcut.

packages/desktop/src-tauri/src/main.rs

@@ -115,7 +115,6 @@ const MENU_ITEM_SETTINGS_ID: &str = "menu_settings";
 #[cfg(target_os = "macos")]
 const MENU_ITEM_COMMAND_PALETTE_ID: &str = "menu_command_palette";
 #[cfg(target_os = "macos")]
-const MENU_ITEM_QUICK_OPEN_ID: &str = "menu_quick_open";
 #[cfg(target_os = "macos")]
 const MENU_ITEM_NEW_SESSION_ID: &str = "menu_new_session";
 #[cfg(target_os = "macos")]
@@ -394,14 +393,6 @@ fn build_macos_menu<R: tauri::Runtime>(
         MENU_ITEM_COMMAND_PALETTE_ID,
         "Command Palette",
         true,
-        Some("Cmd+K"),
-    )?;
-
-    let quick_open = MenuItem::with_id(
-        app,
-        MENU_ITEM_QUICK_OPEN_ID,
-        "Quick Open…",
-        true,
         Some("Cmd+P"),
     )?;
 
@@ -592,7 +583,6 @@ fn build_macos_menu<R: tauri::Runtime>(
                     &PredefinedMenuItem::separator(app)?,
                     &settings,
                     &command_palette,
-                    &quick_open,
                     &PredefinedMenuItem::separator(app)?,
                     &PredefinedMenuItem::services(app, None)?,
                     &PredefinedMenuItem::separator(app)?,
@@ -3885,11 +3875,6 @@ fn main() {
                     dispatch_menu_action(app, "command-palette");
                     return;
                 }
-                if id == MENU_ITEM_QUICK_OPEN_ID {
-                    dispatch_menu_action(app, "quick-open");
-                    return;
-                }
-
                 if id == MENU_ITEM_NEW_SESSION_ID {
                     dispatch_menu_action(app, "new-session");
                     return;