verify: block on commands, with optional onFail remediation

[8bitAlex]

Add an optional verify: top-level block to profile and repo configs. Each entry asserts that a dependency or environmental precondition is working, with an optional automated remediation path. Doctor (tracked in #42) can later aggregate all verifies into an overall health report.

Schema

  verify:
    - name: Node installed
      tasks:
        - type: Shell
          cmd: node --version
      onFail:
        - type: Shell
          cmd: nvm install --lts

Behavior

• All tasks in tasks: must exit 0 → verify passes
• Any non-zero → failed; if onFail is present, run those tasks in order, then re-run tasks: once
• Success on the second pass counts as remediated; second failure is reported

Acceptance criteria

• New optional field verify: on top-level
• Each entry: name: string, tasks: []Task, optional onFail: []Task
• Template raid init includes a commented verify example with the "keep it short and simple" guidance from the original ticket
• JSON Schema updated
• Doctor integration is tracked in the doctor issue (Polished doctor output — formatting, fix hints, summary #42), not in scope here