feat(floating-ai): step 5 — add ai:action IPC side-channel

Add a new ai:action IPC channel so the renderer can react to AI tool
side-effects (task creation, checkpoint/task suggestions). Also mark
AI-created tasks with isAiSuggested: 1 in both project and global
add_task tools.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/renderer/lib/ipcLink.ts

@@ -15,6 +15,7 @@ interface ElectronTRPC {
 
 interface ElectronAI {
   onStreamChunk: (cb: (data: { token: string; done: boolean }) => void) => () => void;
+  onAction: (cb: (data: { type: string; taskId?: string; count?: number }) => void) => () => void;
 }
 
 declare global {