Feature request: additional triggers for automations

Problem

Codex automations are useful for scheduled or heartbeat-style follow-up, but that leaves a gap for workflows that should start from an event instead of a timer.

Request

Support additional trigger types for automations beyond scheduled/heartbeat runs.

Examples that would be useful:

• manual trigger from the UI
• webhook or external event trigger
• issue / pull request / label / comment trigger
• file or repository change trigger
• trigger from another automation completing

Why this matters

A lot of follow-up work is event-driven rather than time-driven. Being able to say "run this when X happens" would avoid polling and make automations fit more real workflows.

Example use cases

• Start a follow-up when a GitHub issue gets labeled.
• Run a one-off automation without converting it into a cron schedule.
• Chain one automation to another when the first one completes.
• Kick off work when a tracked file or workspace state changes.

If there is already a preferred mechanism for event-driven automations, happy to adapt to that model.