fix(hooks): expose typed gateway startup context

docs/.generated/plugin-sdk-api-baseline.sha256

@@ -1,2 +1,2 @@
-ba9b9d9b321b405fef89d4e95c1a3d629d1b956398a5b2a7f25b2a7654879783  plugin-sdk-api-baseline.json
-8bbbee0ea2326148d4fd49f61fe74f83c5bb24c0742cfbf3609f43939fcd4c34  plugin-sdk-api-baseline.jsonl
+475eafc1885c69203ac690a0ef3c1d1ddf6879d904a6980cf5f172c29ed70868  plugin-sdk-api-baseline.json
+906bb0b167b155d2f766bd13f720c8c6ed8f349769d39f57ff5070045b96ef4c  plugin-sdk-api-baseline.jsonl

docs/plugins/sdk-overview.md

@@ -462,6 +462,7 @@ AI CLI backend such as `codex-cli`.
 - `message_sending`: returning `{ cancel: false }` is treated as no decision (same as omitting `cancel`), not as an override.
 - `message_received`: use the typed `threadId` field when you need inbound thread/topic routing. Keep `metadata` for channel-specific extras.
 - `message_sending`: use typed `replyToId` / `threadId` routing fields before falling back to channel-specific `metadata`.
+- `gateway_start`: use `ctx.config`, `ctx.workspaceDir`, and `ctx.getCron?.()` for gateway-owned startup state instead of relying on internal `gateway:startup` hooks.
 
 ### API object fields