punk-supervisor: no task dependency ordering (depends_on)

[t3chn]

Problem

Tasks cannot declare dependencies on other tasks. All tasks dispatched in parallel regardless of logical ordering.

Example

MVP-08 (adjutant init) depends on MVP-06 (db.rs) and MVP-07 (cli.rs). But all 3 were dispatched simultaneously because punk-supervisor has no dependency mechanism.

Proposal

Add optional depends_on field to task.json:

{
  "task_id": "adjutant-mvp-08",
  "depends_on": ["adjutant-mvp-06", "adjutant-mvp-07"],
  "prompt": "..."
}

Supervisor holds dependent tasks in new/ until all dependencies are in done/ with exit_code 0.

Workaround

Manual sequencing: wait for first batch, then create next batch.