feat: Add complete keyboard navigation system

Implemented a full keyboard navigation system with directional commands (C-h/j/k/l) for moving between views,
vim-style navigation (j/k for rows, h/l for columns), and TAB cycling.
Added table header navigation mode where users can move between columns and change sort order with keyboard shortcuts.
The navigation follows visual position: left sidebar, table, and filter bar can all be reached with directional keys.

Created a keymap system with context-aware bindings that resolve commands based on
current focus (Table, TableHeaders, FilterBar, Sidebar).
Commands are dispatched through a centralized handler that manages focus transitions and view state.
Added helper methods to cycle through column headers with proper wrapping.

Auto-select first task on load when tasks exist, and set initial window focus so keyboard shortcuts
work immediately without requiring a mouse click.

src/components/input/mod.rs

@@ -88,6 +88,11 @@ impl Input {
         cx.notify();
     }
 
+    pub fn blur(&self, window: &mut gpui::Window, cx: &mut gpui::Context<Self>) {
+        window.blur();
+        cx.notify();
+    }
+
     fn word_start_before(&self, pos: usize) -> usize {
         if pos == 0 {
             return 0;
@@ -300,6 +305,10 @@ impl Input {
         let ctrl = event.keystroke.modifiers.control;
         let shift = event.keystroke.modifiers.shift;
 
+        if ctrl && (key == "h" || key == "l") {
+            return;
+        }
+
         match key {
             "enter" => {
                 if self.suggestions_open {