v0.9.4

Internal

• Hardened mutation-test coverage for the shared engine orchestration core: generate.ts (77.6% -> 95.79%) and tool_loop.ts (83.7% -> 94.59%), via new test suites for streaming dispatch, HITL approval, schema repair, cost/finish accounting, and the timeout/retry machinery.
• Ratcheted the Stryker break/low thresholds from 83 to 84 (full-repo score now 88.33%); documented the remaining equivalent/unreachable mutants inline with Stryker disable annotations rather than adding runtime guards.