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/claude-code-hooks/handlers/session-event-handler.ts

@@ -3,7 +3,7 @@ import { loadClaudeHooksConfig } from "../config"
 import { loadPluginExtendedConfig } from "../config-loader"
 import { executeStopHooks, type StopContext } from "../stop"
 import type { PluginConfig } from "../types"
-import { isHookDisabled, log } from "../../../shared"
+import { createInternalAgentTextPart, isHookDisabled, log } from "../../../shared"
 import {
 	clearSessionHookState,
 	sessionErrorState,
@@ -94,7 +94,7 @@ export function createSessionEventHandler(ctx: PluginInput, config: PluginConfig
 					.prompt({
 						path: { id: sessionID },
 						body: {
-							parts: [{ type: "text", text: stopResult.injectPrompt }],
+							parts: [createInternalAgentTextPart(stopResult.injectPrompt)],
 						},
 						query: { directory: ctx.directory },
 					})