Integration test coverage: 12 untested src/ modules

[jeremymanning]

Description

The audit identified 12 src/ modules with NO integration test coverage in tests/:

1. src/acceptable_use/ — workload classification and filtering
2. src/agent/ — donor agent lifecycle, identity, mesh LLM
3. src/cli/ — CLI subcommands
4. src/credits/ — NCU caliber classes, credit computation
5. src/data_plane/ — CID store, erasure coding, staging
6. src/ledger/ — CRDT ledger, transparency anchoring
7. src/network/ — P2P discovery, gossip, NAT, TLS, rate limiting
8. src/preemption/ — sovereignty events, idle detection, supervisor
9. src/registry/ — approved artifact registry, release channels
10. src/scheduler/ — job/task state machines, broker, coordinator
11. src/telemetry/ — OpenTelemetry, PII redaction
12. src/verification/ — attestation, trust score, quorum

Some modules have inline #[cfg(test)] unit tests, but no integration-level coverage.

Additionally, 7 existing test files have only 1-2 tests each and 3 empty test directories exist (tests/contract/, tests/integration/, tests/unit/).

Requirements

• Each module gets at least one integration test that exercises the module through its public API
• Tests use real inputs and real outputs (Principle V — no mocks)
• Empty directories are either populated or removed
• Minimal test files are expanded to cover edge cases

Success Criteria

• Every src/ module has at least one corresponding integration test
• Empty test directories removed or populated
• Each test file has at least 3 meaningful tests
• All tests pass on CI (Linux, macOS, Windows where applicable)
• Test count increases by at least 50 from current 489+

Testing (Principle V)

• Agent lifecycle: real enrollment → heartbeat → pause → withdraw
• Credits: real NCU computation with known hardware profiles
• Data plane: real CID store operations, real erasure encode/decode
• Network: real mDNS discovery on LAN, real STUN queries
• Preemption: real keyboard event simulation → SIGSTOP timing
• Scheduler: real job submission → matching → dispatch → result

[jeremymanning]

Addressed in spec 004-full-implementation (PR #59). Implementation verified in code; 802 tests passing across Linux/macOS/Windows. See #57 master plan for full context.