feat: add k-launcher-ui-egui crate for enhanced UI

- Introduced a new crate `k-launcher-ui-egui` to provide a graphical user interface using eframe and egui.
- Updated the workspace configuration in `Cargo.toml` to include the new crate.
- Implemented the main application logic in `src/app.rs`, handling search functionality and user interactions.
- Created a library entry point in `src/lib.rs` to expose the `run` function for launching the UI.
- Modified the `k-launcher` crate to include a new binary target for the egui-based launcher.
- Added a new main file `src/main_egui.rs` to initialize and run the egui UI with the existing kernel and launcher components.

crates/k-launcher-ui-egui/src/app.rs

@@ -0,0 +1,182 @@
+use std::sync::{Arc, mpsc};
+
+use egui::{Color32, Key, ViewportCommand};
+use k_launcher_kernel::{AppLauncher, SearchEngine, SearchResult};
+use k_launcher_os_bridge::WindowConfig;
+
+const BG: Color32 = Color32::from_rgba_premultiplied(20, 20, 30, 230);
+const BORDER_CYAN: Color32 = Color32::from_rgb(0, 183, 235);
+const SELECTED_BG: Color32 = Color32::from_rgba_premultiplied(0, 100, 140, 180);
+const DIM_TEXT: Color32 = Color32::from_rgb(180, 185, 200);
+
+pub struct KLauncherApp {
+    engine: Arc<dyn SearchEngine>,
+    launcher: Arc<dyn AppLauncher>,
+    query: String,
+    results: Vec<SearchResult>,
+    selected: usize,
+    rt: tokio::runtime::Handle,
+    result_tx: mpsc::SyncSender<Vec<SearchResult>>,
+    result_rx: mpsc::Receiver<Vec<SearchResult>>,
+}
+
+impl KLauncherApp {
+    fn new(
+        engine: Arc<dyn SearchEngine>,
+        launcher: Arc<dyn AppLauncher>,
+        rt: tokio::runtime::Handle,
+    ) -> Self {
+        let (result_tx, result_rx) = mpsc::sync_channel(4);
+        Self {
+            engine,
+            launcher,
+            query: String::new(),
+            results: vec![],
+            selected: 0,
+            rt,
+            result_tx,
+            result_rx,
+        }
+    }
+
+    fn trigger_search(&self, query: String) {
+        let engine = self.engine.clone();
+        let tx = self.result_tx.clone();
+        self.rt.spawn(async move {
+            let results = engine.search(&query).await;
+            let _ = tx.send(results);
+        });
+    }
+}
+
+impl eframe::App for KLauncherApp {
+    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
+        if let Ok(results) = self.result_rx.try_recv() {
+            self.results = results;
+        }
+
+        let mut close = false;
+        let mut launch_selected = false;
+
+        ctx.input(|i| {
+            if i.key_pressed(Key::Escape) {
+                close = true;
+            }
+            if i.key_pressed(Key::Enter) {
+                launch_selected = true;
+            }
+            if i.key_pressed(Key::ArrowDown) {
+                let len = self.results.len();
+                if len > 0 {
+                    self.selected = (self.selected + 1).min(len - 1);
+                }
+            }
+            if i.key_pressed(Key::ArrowUp) {
+                if self.selected > 0 {
+                    self.selected -= 1;
+                }
+            }
+        });
+
+        if close {
+            ctx.send_viewport_cmd(ViewportCommand::Close);
+            return;
+        }
+
+        if launch_selected {
+            if let Some(result) = self.results.get(self.selected) {
+                if let Some(on_select) = &result.on_select {
+                    on_select();
+                }
+                self.launcher.execute(&result.action);
+            }
+            ctx.send_viewport_cmd(ViewportCommand::Close);
+            return;
+        }
+
+        let frame = egui::Frame::new()
+            .fill(BG)
+            .stroke(egui::Stroke::new(1.0, BORDER_CYAN))
+            .inner_margin(egui::Margin::same(12))
+            .corner_radius(egui::CornerRadius::same(8));
+
+        egui::CentralPanel::default().frame(frame).show(ctx, |ui| {
+            let response = ui.add_sized(
+                [ui.available_width(), 36.0],
+                egui::TextEdit::singleline(&mut self.query)
+                    .hint_text("Search...")
+                    .font(egui::TextStyle::Heading),
+            );
+
+            if response.changed() {
+                self.selected = 0;
+                self.trigger_search(self.query.clone());
+            }
+
+            response.request_focus();
+
+            ui.add_space(8.0);
+
+            if self.results.is_empty() && !self.query.is_empty() {
+                ui.add_space(20.0);
+                ui.with_layout(egui::Layout::top_down(egui::Align::Center), |ui| {
+                    ui.colored_label(DIM_TEXT, "No results");
+                });
+                return;
+            }
+
+            egui::ScrollArea::vertical().show(ui, |ui| {
+                ui.set_width(ui.available_width());
+                for (i, result) in self.results.iter().enumerate() {
+                    let is_selected = i == self.selected;
+                    let bg = if is_selected { SELECTED_BG } else { Color32::TRANSPARENT };
+
+                    let row_frame = egui::Frame::new()
+                        .fill(bg)
+                        .inner_margin(egui::Margin { left: 8, right: 8, top: 6, bottom: 6 })
+                        .corner_radius(egui::CornerRadius::same(4));
+
+                    row_frame.show(ui, |ui| {
+                        ui.set_width(ui.available_width());
+                        ui.horizontal(|ui| {
+                            ui.add_space(8.0);
+                            ui.vertical(|ui| {
+                                ui.label(result.title.as_str());
+                                if let Some(desc) = &result.description {
+                                    ui.colored_label(DIM_TEXT, desc);
+                                }
+                            });
+                        });
+                    });
+
+                    ui.add_space(2.0);
+                }
+            });
+        });
+    }
+}
+
+pub fn run(
+    engine: Arc<dyn SearchEngine>,
+    launcher: Arc<dyn AppLauncher>,
+) -> Result<(), eframe::Error> {
+    let wc = WindowConfig::launcher();
+    let rt = tokio::runtime::Runtime::new().expect("tokio runtime");
+    let handle = rt.handle().clone();
+
+    let options = eframe::NativeOptions {
+        viewport: egui::ViewportBuilder::default()
+            .with_inner_size([wc.width, wc.height])
+            .with_decorations(wc.decorations)
+            .with_transparent(wc.transparent)
+            .with_resizable(wc.resizable)
+            .with_always_on_top(),
+        ..Default::default()
+    };
+
+    eframe::run_native(
+        "K-Launcher",
+        options,
+        Box::new(move |_cc| Ok(Box::new(KLauncherApp::new(engine, launcher, handle)))),
+    )
+}

crates/k-launcher-ui-egui/src/lib.rs

@@ -0,0 +1,12 @@
+mod app;
+
+use std::sync::Arc;
+
+use k_launcher_kernel::{AppLauncher, SearchEngine};
+
+pub fn run(
+    engine: Arc<dyn SearchEngine>,
+    launcher: Arc<dyn AppLauncher>,
+) -> Result<(), eframe::Error> {
+    app::run(engine, launcher)
+}