fix: gmail pageToken reuse + slack bot token unhandled rejection

[meidad]

Summary

Two daemon-startup regressions that surfaced after #53 merged:

Gmail Invalid pageToken on every delta run

The pipeline stores lastMessage.id as the cursor and passes it back to the source on the next run; the Gmail source was treating that as Gmail's pageToken. They're different beasts — message IDs are short hex strings, pageTokens are opaque intra-run pagination handles. Cross-run reuse always 400s with Invalid pageToken.

Fix: stop using the inherited cursor as pageToken in src/ingest/sources/gmail.ts. Re-running the same q: is safe because the pipeline's per-message dedup step rejects already-stored messages, so a fresh full scan is idempotent (verified: 4 messages skipped via dedup on a re-run). Delta semantics come from options.since (computed by the ingest scheduler from the last successful job), which still works.

Slack User adapter account_inactive unhandled rejection

When the workspace's bot token was deactivated, the bot client's own auth.test() was wrapped in try/catch, but the Bolt App was being constructed with the bad bot token before validation. Bolt's internal auth.test fired an uncaught promise.

Fix: validate the bot token via botClient.auth.test() before handing it to Bolt in src/daemon/channels/slack-user.ts. On failure, drop the bot client and fall back to the user token for Bolt's Socket Mode connection. Same user-facing behavior (agent posts as user), just no more stack trace at startup.

Test plan

• Run `pnpm dev ingest gmail --since 2026-05-25 --run-type delta` against an install with a stored `last_cursor`; verify no `Invalid pageToken` and messages either ingest or are skipped by dedup.
• Run `pnpm dev ingest gmail --since 2026-05-25` from scratch; verify clean ingest end-to-end.
• Restart the daemon with a workspace whose bot token has been deactivated (or invalidate it intentionally); verify the log shows `Bot token auth failed -- agent will post as user` instead of an unhandled rejection stack trace, and that the user-mode adapter still starts cleanly.

🤖 Generated with Claude Code