fix(copilot): mark internal hook injections as agent-initiated

Apply the internal initiator marker to automated continuation, recovery, babysitter, stop-hook, and hook-message injections so Copilot attribution consistently sets x-initiator=agent for system-generated prompts.

src/hooks/session-recovery/resume.test.ts

@@ -1,6 +1,7 @@
 declare const require: (name: string) => any
 const { describe, expect, test } = require("bun:test")
 import { extractResumeConfig, resumeSession } from "./resume"
+import { OMO_INTERNAL_INITIATOR_MARKER } from "../../shared/internal-initiator-marker"
 import type { MessageData } from "./types"
 
 describe("session-recovery resume", () => {
@@ -44,5 +45,8 @@ describe("session-recovery resume", () => {
     // then
     expect(ok).toBe(true)
     expect(promptBody?.tools).toEqual({ question: false, bash: true })
+    expect(Array.isArray(promptBody?.parts)).toBe(true)
+    const firstPart = (promptBody?.parts as Array<{ text?: string }>)?.[0]
+    expect(firstPart?.text).toContain(OMO_INTERNAL_INITIATOR_MARKER)
   })
 })