Ship installable Tailnet client in v0.1.8

[lyc-aon]

Summary

• add a hosted PWA manifest, icons, phone install action, and standalone reload action
• fix active-turn Queue and Steer by keeping revision guards off revision-optional commands while preserving prompt leases
• describe Fast mode as a provider-priority request without implying lower reasoning effort
• remove the arbitrary physical line-count gate
• bump the complete release contract to v0.1.8

Verification

• pnpm check
• pnpm test:tooling
• pnpm test
• pnpm test:e2e (15 passed)
• pnpm build
• pnpm test:packaging
• live OMP 16.5.0 repro: stale-revision Steer rejected; revisionless Steer and Follow-up accepted
• Chrome manifest parser: no manifest errors

Deployment

After merge and tag publication, rebuild and reinstall the Tailnet gateway from main, then verify the live manifest, icons, install action, upstream health, and Funnel-off state.