test: Add tests for critical untested source files

[dean0x]

Problem

Several critical source files have no test coverage. These are core infrastructure components that would benefit from behavioral tests before public launch.

Scope

Tier 1 — Launch priority (complex, high-risk)

File	Lines	Why
task-manager.ts	510	Orchestrates entire task lifecycle
event-driven-worker-pool.ts	520	Worker pool with autoscaling
worktree-manager.ts	691	Git worktree isolation

Tier 2 — Important (medium complexity)

File	Lines	Why
autoscaling-manager.ts	342	Dynamic worker scaling
resource-monitor.ts	445	System resource monitoring
recovery-manager.ts	—	Error recovery logic
container.ts	—	DI container

Tier 3 — Post-launch (lower risk)

• Utils, output-repository, github-integration, logger

Testing Approach

• Follow existing patterns: mock dependencies, test behaviors not implementation
• Use MockWorkerPool, MockProcessSpawner patterns from existing tests
• Focus on: happy paths, error paths, edge cases, event emissions
• Each test file should be added to the appropriate test group in package.json

Cross-Reference

Issue #31 items that may overlap:

• Timing-based test waits (addressed in some files)
• QueryHandler workaround
• findByStatus pagination

These should be addressed opportunistically during this work.

Acceptance Criteria

• Tier 1 files have >80% branch coverage
• Tier 2 files have >60% branch coverage
• Tests follow existing patterns (mocks, behavioral testing)
• All new tests are in appropriate test groups
• No timing-based waits in new tests

Dependencies

• Depends on Biome setup (new tests should conform to lint rules from day 1)