feat(coding-agent): add named-only filter toggle to /resume picker (#1128)

Adds Ctrl+N toggle to filter sessions by named-only vs all in the /resume picker.

- Add NameFilter type and filtering logic to session-selector-search.ts
- Add toggleSessionNamedFilter app keybinding (default: ctrl+n)
- Show Name: All/Named state in header
- Empty state mentions toggle keybinding as escape hatch
- Export hasSessionName() to avoid duplication

Co-authored-by: warren <warren.winter@gmail.com>

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -3497,6 +3497,7 @@ export class InteractiveMode {
 						mgr.appendSessionInfo(next);
 					},
 					showRenameHint: true,
+					keybindings: this.keybindings,
 				},
 
 				this.sessionManager.getSessionFile(),