[AZ-505] Cycle 6 Step 17: retrospective + close cycle

Single-task cycle delivering AZ-505 (3 SP); 1 batch, PASS verdict
after a single auto-fix round (ComputeLocationHash duplication
consolidated into Uuidv5.LocationHashForTile). Step 14 Security
Audit skipped; Step 15 Performance Test PASS (8/8, exit 0) and
closes the cycle-3 perf-harness leftover that carried across
cycles 3-5.

Top 3 lessons appended to LESSONS.md ring buffer:
- Kestrel Http1AndHttp2 requires TLS for ALPN; spec-time decision
- Dapper-bypassing test paths own the Npgsql type contract
- Test fixtures naming specific schema artifacts need migration awareness

Cycle 7 opens at Step 9 (New Task).

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/_autodev_state.md

@@ -2,14 +2,14 @@
 
 ## Current Step
 flow: existing-code
-step: 17
-name: Retrospective
+step: 9
+name: New Task
 status: not_started
 sub_step:
   phase: 0
   name: awaiting-invocation
   detail: ""
 retry_count: 0
-cycle: 6
+cycle: 7
 tracker: jira
 auto_push: true