feat: make session selector keybindings configurable (#948)

I lost my ability to select up and down in the session selector because
of some hardcoded keybindings again... So, I am adding these
configurable keybindings so I can `ctrl+p` to select up :-)

### Changes

Adds 4 new keybinding actions for the session picker (/resume):
- `toggleSessionPath` (ctrl+p) - toggle path display
- `toggleSessionSort` (ctrl+r) - toggle sort mode
- `deleteSession` (ctrl+d) - delete selected session
- `deleteSessionNoninvasive` (ctrl+backspace) - delete when query empty

Refactors session-selector to use `kb.matches()` instead of hardcoded key checks.

packages/tui/src/keybindings.ts

@@ -41,7 +41,13 @@ export type EditorAction =
 	// Undo
 	| "undo"
 	// Tool output
-	| "expandTools";
+	| "expandTools"
+	// Session
+	| "toggleSessionPath"
+	| "toggleSessionSort"
+	| "renameSession"
+	| "deleteSession"
+	| "deleteSessionNoninvasive";
 
 // Re-export KeyId from keys.ts
 export type { KeyId };
@@ -95,6 +101,12 @@ export const DEFAULT_EDITOR_KEYBINDINGS: Required<EditorKeybindingsConfig> = {
 	undo: "ctrl+-",
 	// Tool output
 	expandTools: "ctrl+o",
+	// Session
+	toggleSessionPath: "ctrl+p",
+	toggleSessionSort: "ctrl+s",
+	renameSession: "ctrl+r",
+	deleteSession: "ctrl+d",
+	deleteSessionNoninvasive: "ctrl+backspace",
 };
 
 /**