refactor(tools/call-omo-agent): split tools.ts into focused modules under 200 LOC

- Extract getMessageDir to message-dir.ts
- Extract executeBackground to background-executor.ts
- Extract session creation logic to session-creator.ts
- Extract polling logic to completion-poller.ts
- Extract message processing to message-processor.ts
- Create sync-executor.ts to orchestrate sync execution
- Add ToolContextWithMetadata type to types.ts
- tools.ts now <200 LOC and focused on tool definition

src/tools/call-omo-agent/message-dir.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
+}