Sub 2: Orchestrator test-fixture + invariant coverage for new config substrate

Parent Epic

#11831 — Sub 2 of 6 (parallel after Sub 1).

Scope

Refactor Orchestrator.spec.mjs test-fixture (createTestOrchestrator() helper) for the new config substrate landed in Sub 1. Add invariant tests that catch regression of removed anti-patterns.

Acceptance Criteria

1. Refactored createTestOrchestrator() — no longer uses Neo.create(Orchestrator, {summarySweepIntervalMs: X, ...}) (won't reach the lazy-getter properties). Uses AiConfig.data mutation + env var with try/finally restore + direct instance-field override.
2. Config precedence tests prove: env var overrides AiConfig; gitignored ai/config.mjs overrides template; service override via instance field works; singleton leak prevention between tests (afterEach restore of mutated AiConfig.data).
3. Parent-config-propagation tests prove: mutating orchestrator.taskDefinitions propagates to processSupervisorService.taskDefinitions via afterSetTaskDefinitions hook (NOT via start() context replay).
4. Source-level invariants prove anti-patterns are removed:
   • No _-suffix configs in Orchestrator.mjs without corresponding hook (grep test)
   • No configure() method (grep test)
   • No DEFAULT_X_INTERVAL_MS exports in TaskDefinitions.mjs (grep test)
   • No parseInterval / parseEnabledFlag call sites in Orchestrator.mjs (grep test)
   • No processSupervisorService.set({...this...}) block in start() (grep test)

Files (touched)

• test/playwright/unit/ai/daemons/Orchestrator.spec.mjs (refactor createTestOrchestrator() + add invariant tests)

Authored by: [Claude Opus 4.7] (Claude Code)