feat: restructure k-launcher workspace and add core functionality

- Updated Cargo.toml to include a new k-launcher crate and reorganized workspace members.
- Introduced a README.md file detailing the project philosophy, architecture, and technical specifications.
- Implemented a new Kernel struct in k-launcher-kernel for managing plugins and search functionality.
- Created a Plugin trait for plugins to implement, allowing for asynchronous search operations.
- Developed k-launcher-ui with an Iced-based UI for user interaction, including search input and result display.
- Added AppsPlugin and CalcPlugin to handle application launching and basic calculations, respectively.
- Established a theme module for UI styling, focusing on an Aero aesthetic.
- Removed unnecessary main.rs files from plugin crates, streamlining the project structure.

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

@@ -0,0 +1,179 @@
+use std::sync::Arc;
+
+use iced::{
+    Color, Element, Length, Size, Subscription, Task,
+    keyboard::{self, Event as KeyEvent, Key, key::Named},
+    widget::{column, container, image, row, scrollable, svg, text, text_input, Space},
+    window,
+};
+
+use k_launcher_kernel::{Kernel, SearchResult};
+
+use crate::theme::AeroColors;
+
+static INPUT_ID: std::sync::LazyLock<iced::widget::Id> =
+    std::sync::LazyLock::new(|| iced::widget::Id::new("search"));
+
+pub struct KLauncherApp {
+    kernel: Arc<Kernel>,
+    query: String,
+    results: Arc<Vec<SearchResult>>,
+    selected: usize,
+}
+
+impl KLauncherApp {
+    fn new(kernel: Arc<Kernel>) -> Self {
+        Self {
+            kernel,
+            query: String::new(),
+            results: Arc::new(vec![]),
+            selected: 0,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum Message {
+    QueryChanged(String),
+    ResultsReady(Arc<Vec<SearchResult>>),
+    KeyPressed(KeyEvent),
+}
+
+fn update(state: &mut KLauncherApp, message: Message) -> Task<Message> {
+    match message {
+        Message::QueryChanged(q) => {
+            state.query = q.clone();
+            state.selected = 0;
+            let kernel = state.kernel.clone();
+            Task::perform(
+                async move { kernel.search(&q).await },
+                |results| Message::ResultsReady(Arc::new(results)),
+            )
+        }
+        Message::ResultsReady(results) => {
+            state.results = results;
+            Task::none()
+        }
+        Message::KeyPressed(event) => {
+            let key = match event {
+                KeyEvent::KeyPressed { key, .. } => key,
+                _ => return Task::none(),
+            };
+            let Key::Named(named) = key else {
+                return Task::none();
+            };
+            let len = state.results.len();
+            match named {
+                Named::Escape => std::process::exit(0),
+                Named::ArrowDown => {
+                    if len > 0 {
+                        state.selected = (state.selected + 1).min(len - 1);
+                    }
+                }
+                Named::ArrowUp => {
+                    if state.selected > 0 {
+                        state.selected -= 1;
+                    }
+                }
+                Named::Enter => {
+                    if let Some(result) = state.results.get(state.selected) {
+                        (result.on_execute)();
+                    }
+                    std::process::exit(0);
+                }
+                _ => {}
+            }
+            Task::none()
+        }
+    }
+}
+
+fn view(state: &KLauncherApp) -> Element<'_, Message> {
+    let colors = AeroColors::standard();
+
+    let search_bar = text_input("Search...", &state.query)
+        .id(INPUT_ID.clone())
+        .on_input(Message::QueryChanged)
+        .padding(12)
+        .size(18);
+
+    let result_rows: Vec<Element<'_, Message>> = state
+        .results
+        .iter()
+        .enumerate()
+        .map(|(i, result)| {
+            let is_selected = i == state.selected;
+            let bg_color = if is_selected {
+                colors.border_cyan
+            } else {
+                Color::from_rgba8(255, 255, 255, 0.07)
+            };
+            let icon_el: Element<'_, Message> = match &result.icon {
+                Some(p) if p.ends_with(".svg") =>
+                    svg(svg::Handle::from_path(p)).width(24).height(24).into(),
+                Some(p) =>
+                    image(image::Handle::from_path(p)).width(24).height(24).into(),
+                None => Space::new().width(24).height(24).into(),
+            };
+            container(
+                row![icon_el, text(result.title.as_str()).size(15)]
+                    .spacing(8)
+                    .align_y(iced::Center),
+            )
+                .width(Length::Fill)
+                .padding([6, 12])
+                .style(move |_theme| container::Style {
+                    background: Some(iced::Background::Color(bg_color)),
+                    ..Default::default()
+                })
+                .into()
+        })
+        .collect();
+
+    let results_list =
+        scrollable(column(result_rows).spacing(2).width(Length::Fill)).height(Length::Fill);
+
+    let content = column![search_bar, results_list]
+        .spacing(8)
+        .padding(12)
+        .width(Length::Fill)
+        .height(Length::Fill);
+
+    container(content)
+        .width(Length::Fill)
+        .height(Length::Fill)
+        .style(|_theme| container::Style {
+            background: Some(iced::Background::Color(Color::from_rgba8(
+                20, 20, 30, 0.9,
+            ))),
+            ..Default::default()
+        })
+        .into()
+}
+
+fn subscription(_state: &KLauncherApp) -> Subscription<Message> {
+    keyboard::listen().map(Message::KeyPressed)
+}
+
+pub fn run(kernel: Arc<Kernel>) -> iced::Result {
+    iced::application(
+        move || {
+            let app = KLauncherApp::new(kernel.clone());
+            let focus = iced::widget::operation::focus(INPUT_ID.clone());
+            (app, focus)
+        },
+        update,
+        view,
+    )
+        .title("K-Launcher")
+        .subscription(subscription)
+        .window(window::Settings {
+            size: Size::new(600.0, 400.0),
+            position: window::Position::Centered,
+            decorations: false,
+            transparent: true,
+            resizable: false,
+            ..Default::default()
+        })
+        .run()
+}