Add architecture review findings and address documentation issues

Review of all ADR documents (001-007) and peripheral architecture docs
identified 3 critical, 10 warning, and 7 suggestion issues.

Addressed in this commit:
- W-1: Add draft qualifier to ADR-002 reference to incremental exploration
- W-2: Add Alternatives Considered section to ADR-001
- W-3: Add Document Lifecycle section to README.md (draft/stable/deprecated)
- W-4: Clarify includeCompleted semantics (only 'completed' status triggers exclusion)
- W-5: Document file I/O runtime constraints in frontmatter.md
- W-6: Add ADR reference to architecture.md redirect
- W-7: Verify CVE-2025-64718 (confirmed real, improved description)
- W-9: Convert workspace-absolute paths to relative/monorepo references
- S-7: Add future ADR-008 note to incremental-update-exploration.md

Critical issues (C-1, C-2, C-3) and remaining warnings (W-8, W-10, S-4, S-5)
were addressed by a parallel agent in a prior commit.

All 16 review tasks created and resolved.

tasks/architecture/w-3-doc-lifecycle-protocol.md

@@ -0,0 +1,19 @@
+---
+id: architecture/w-3-doc-lifecycle-protocol
+name: Define document lifecycle states and transition criteria
+status: completed
+depends_on: []
+created: 2026-04-26T09:10:49.101915726Z
+modified: 2026-04-26T09:10:49.101916156Z
+scope: narrow
+risk: low
+---
+
+# Description
+
+**Review ref**: W-3 (Warning)
+**Files affected**: `docs/architecture/frontmatter.md` or `docs/architecture/README.md`
+
+All peripheral docs have `status: draft` but there's no protocol for when they transition to stable, or what "draft" means. Define document lifecycle states (draft → stable → deprecated) and transition criteria in frontmatter.md or a governance section in README.md.
+
+**Source**: `/docs/reviews/architecture-review-2026-04-26.md` W-3