docs: commit all Phase 6 documentation updates and OpenSpec archives

- devops docs: 8 files updated for Phase 6 state; field-trial.md added (946-line runbook)
- developer docs: api-reference (50+ endpoints), quick-start, 5 existing guides updated, 5 new guides added
- engineering docs: all 12 files updated (services, architecture, SDK guide, testing, overview)
- OpenSpec archives: phase-7-devops-field-trial, developer-docs-phase6-update, engineering-docs-phase6-update
- VALIDATOR.md + scripts/start-validator.sh: V&V Architect tooling added
- .gitignore: exclude session artifacts, build artifacts, and agent workspaces

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -9,3 +9,13 @@ coverage/
 # Next.js build output
 portal/.next/
 portal/node_modules/
+portal/tsconfig.tsbuildinfo
+
+# Agent workspace directories
+.cto-workspace/
+.validator-workspace/
+
+# Session artifacts
+conversation_backup.txt
+next_steps.md
+vj_notes/