[AZ-456] [autodev] Implement phase 5 → 6 transition checkpoint

Records that batch 1 = [AZ-456] is computed, file-ownership envelope
resolved, and Jira ticket transitioned to In Progress. Next step:
write the test-infrastructure scaffold (~30 files) and run the fast
+ static profiles. Suggests a session boundary here per Context
Management Protocol so phase 6 starts with fresh context.

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

_docs/_autodev_state.md

@@ -6,9 +6,9 @@ step: 6
 name: Implement Tests
 status: in_progress
 sub_step:
-  phase: 1
-  name: parse
-  detail: ""
+  phase: 6
+  name: implement-tasks-sequentially
+  detail: "batch 1 = AZ-456 (5 pts); tracker In Progress; ~30 files to write"
 retry_count: 0
 cycle: 1
 tracker: jira