test: make the twin host tests fast and deterministic

[kody-w]

Root cause

The Twin shard was running large conversation/approval integration scenarios as single Vitest tests while the host fixture used the production append-only filesystem durability path. On macOS CI that made individual tests do several minutes of repeated canonical store scans, approval/runtime setup, and fsync-heavy commits, so different tests crossed Vitest's 120s per-test timeout depending on runner speed.

Fix

• Keep durable filesystem syncs as the production default, but add an explicit non-durable fixture mode for host integration tests; workspace-store durability/crash tests still exercise the real fsync path.
• Split the broad Twin integration cases into smaller tests that assert the same provider/model/computer/agent/routine/approval rejection behavior and the same agent/routine/settings apply behavior without one test accumulating all work.
• Replace the approval-recommendation Twin test's real guest-runtime setup with canonical pending approval/run evidence, then verify Twin apply still refuses to decide and the explicit Work approval decision path is required.

Timings

Before:

• CI run 36328101083 attempt 2: test/twin.test.ts 827.25s total; failed tests at 120.073s and 136.889s; slow passing tests included 141.498s, 90.027s, 85.108s, 70.486s.
• Local before: 372.51s total; slowest tests 45.921s, 42.181s, 42.146s, 42.036s.

After:

• Local after: 160.41s total; slowest tests 18.433s, 17.333s, 16.230s.
• CI green attempt: 480.90s total; slowest tests 54.646s, 53.537s, 53.248s, all below the 120s per-test timeout.

Validation

• npm --workspace @rapp-work/host run build
• npm --workspace @rapp-work/host test -- --run test/twin.test.ts --reporter=verbose
• npm --workspace @rapp-work/host run typecheck
• npm --workspace @rapp-work/workspace-store test -- --run
• targeted production regression: npm --workspace @rapp-work/host test -- --run test/production.test.ts --reporter=verbose -t "approval can be cancelled"
• privacy scan before push: denylist_scan.py diff <clone> origin/main => 0 findings

Green CI

• Full CI: https://github.com/kody-w/openrappter/actions/runs/36336543646 (success)
• Release Constitution: https://github.com/kody-w/openrappter/actions/runs/36336543638 (success)
• Twin green feat: macOS menu bar companion app #1: https://github.com/kody-w/openrappter/actions/runs/36336543646/job/108668365817
• Twin green feat: Add WatchmakerAgent with self-evolving agent ecosystem #2: https://github.com/kody-w/openrappter/actions/runs/36336543646/job/108671960947
• Twin green feat: Agent ecosystem expansion — v1.5.0 #3: https://github.com/kody-w/openrappter/actions/runs/36336543646/job/108674942089