refactor(call-omo-agent): split tools.ts into agent execution modules

Extract agent call pipeline:
- agent-type-normalizer.ts, tool-context-with-metadata.ts
- subagent-session-creator.ts, subagent-session-prompter.ts
- sync-agent-executor.ts, background-agent-executor.ts
- session-completion-poller.ts, session-message-output-extractor.ts
- message-storage-directory.ts

src/tools/call-omo-agent/message-storage-directory.ts

@@ -0,0 +1,18 @@
+import { existsSync, readdirSync } from "node:fs"
+import { join } from "node:path"
+import { MESSAGE_STORAGE } from "../../features/hook-message-injector"
+
+export function getMessageDir(sessionID: string): string | null {
+	if (!sessionID.startsWith("ses_")) return null
+	if (!existsSync(MESSAGE_STORAGE)) return null
+
+	const directPath = join(MESSAGE_STORAGE, sessionID)
+	if (existsSync(directPath)) return directPath
+
+	for (const dir of readdirSync(MESSAGE_STORAGE)) {
+		const sessionPath = join(MESSAGE_STORAGE, dir, sessionID)
+		if (existsSync(sessionPath)) return sessionPath
+	}
+
+	return null
+}