Use Corbits Tag for Slack approval workflows

[pratikbuilds]

Summary

• Move the Slack approval workflow to mountSlackTag
• Render approval controls with Chat SDK cards and actions
• Resume or cancel the local Interchange run from Slack actions
• Remove the unused shared Slack bridge

Testing

• bun run --filter '*' typecheck
• Bundled the registered starter command-line entry points
• Verified the complete approval flow in Slack

Dependency

Depends on #14. This branch is authored directly on top of its head commit.

[pvams]

MIT -> LGPL-2.1

[TheGreatAxios]

Code Approved - but please update Interchange -> Corbits text for the tag

[TheGreatAxios]

Self-review (agent)

Verdict: Approve

What this PR does

Moves the Slack approval workflow onto Corbits Tag + Chat SDK cards/actions. Deletes the unused shared Bolt bridge (src/slack/*, adapter, block kit helpers). Approvals resume or cancel the local Interchange run from button actions. Reuses the shared Tag workspace from #14 (no second gitlink).

Findings

Severity	Finding
minor	Stale/forged/already-decided actions silently no-op — no ephemeral feedback. #22 later adds “This approval is no longer active.” for this sibling; worth either landing that here or accepting as stack follow-up.
minor	Decision correlation uses runId button value + thread map, but not message-id binding. Adequate for a starter; post-to-X’s correlation is stronger.
minor	No session unit tests on the rewrite (draft failure, stale action, double-click).
nit	cli.ts closes over chat before const chat = mounted.bot (safe if onTag is never sync — same sibling pattern).

What looks solid

• Double-click: decision is set before await signal/cancel; reset on error
• Start-card post failure cancels the run and drops the active map entry
• Config drops Socket Mode appToken; validates port + signing secret + bot token at startup
• Incremental scope is cleanly starter/slack-approval-flow/** against #14

Checks

• Full read of session.ts, cards.ts, cli.ts, config.ts, workflow.ts
• git diff --name-status base…HEAD — bridge fully deleted
• Live Slack approval flow not re-exercised in this review

No blockers. Squash-on-merge recommended for stack merge noise.