v8.4.0-dev.11

• Merge pull request #1568 from kaitranntt/kai/feat/maintainability-traceability-epic
• fix(logging): harden structured trace redaction
• docs(hardening): finalize epic metrics + progress log (P1-P7)
• refactor: P6 god-file splits (quota-fetcher + quota-fetcher-gemini-cli; 4 deferred)
• feat(lint): P7 enforcement gates (no-new-throw-error + max-lines) + docs
• refactor: P5 god-file splits (test-backed, public API preserved)
• feat(errors): P4 typed-error taxonomy adoption (0->91% locked) + erasable-syntax fix
• feat(logging): P3 hotpath console.error migration + redaction gate (928->267)
• feat(logging): P2 traceability foundation - requestId wrap, daemon forwarding (#NNN)
• feat(hardening): P1 maintainability metrics baseline + freshness gate (#1561)