Integrate Composio for external tool access

Agents can now call external tools (GitHub, Slack, Gmail, etc.) via
Composio's managed API. A thin HTTP client calls the Composio REST API
directly — no heavy SDK dependency. External tools are loaded per-org
from composio_settings and merged with internal tools at run time. The
agent run loop routes composio_* tool calls to the Composio execution
endpoint while internal tools dispatch as before.

Includes: migration 043 for composio_settings table, IPC handler for
saving Composio API key and toolkit configuration, and the composio
client/bridge modules.

AgentCompany-New/src/preload/index.ts

@@ -82,6 +82,7 @@ const api: DesktopApi = {
   setLegalHoldState: (input) => invoke(IPC_CHANNELS.setLegalHoldState, input),
   createRetentionFreeze: (input) => invoke(IPC_CHANNELS.createRetentionFreeze, input),
   setRetentionFreezeState: (input) => invoke(IPC_CHANNELS.setRetentionFreezeState, input),
+  saveComposioSettings: (input) => invoke(IPC_CHANNELS.saveComposioSettings, input),
   search: (input) => invoke(IPC_CHANNELS.search, input),
   subscribe: (callback) => {
     const listener = (_event: Electron.IpcRendererEvent, payload: RendererEvent) => callback(payload);