Harden durable runner long-run controls

[HomenShum]

Summary

• port long-run runner hardening into the merged runner.ts path
• fail closed on unknown plan keys and embedded token-shaped secrets
• add explicit --clear-stale-lock, lock-held/stale UX, torn-tail ledger repair, runner report, exit code 3 for budget exhaustion, and stronger ledger redaction
• bump package metadata to 0.3.0 for the next npm publish

Proof

• npm test
• npm pack + clean-temp npm exec --package <tarball> -- proofloop doctor --json
• clean-temp packed proofloop runner report --run-id latest exits 2 with expected missing-run state

Not done

• npm publish is blocked locally by npm whoami E401; this PR prepares 0.3.0, but registry publication still needs npm auth.

Closes #7 after merge and npm publish.