Session 27 Part 4: Final completion summary (PR ready for merge)

- SESSION-27-FINAL-SUMMARY.md: Comprehensive 4-part session summary
- SESSION-27-PART-4-PLAN.md: PR preparation plan
- All work committed across 7 commits (4,684 lines)
- PR ready: main...feat/session-26-agent-experience
- Production operational: 10/11 endpoints (90%)

Session 27 complete: 1h07m, 4 DPDCA cycles, awaiting manual PR merge.

Author: MarcoPolo483