feat(DIS-104): global semaphore for max_concurrent_agents cap
docs(DIS-110): add cli-feature-probe.md for Phase 2 sanity checks
chore(DIS-109): add vitest.config.ts, complete .env.example, test scripts
feat(DIS-101): introduce pino structured logger, remove console.*
feat(DIS-104): global semaphore for max_concurrent_agents cap
docs(DIS-110): add cli-feature-probe.md for Phase 2 sanity checks
chore(DIS-109): add vitest.config.ts, complete .env.example, test scripts