handoff: VSync/event-wedge fixes + iterate 2.A–2.BC research notes

Source changes (dormant parity infra, retained from iterate 2.AI/2.AO):
- xenia-kernel/exports.rs: nt_create_event manual_reset polarity +
  related event wiring
- xenia-gpu/mmio_region.rs: D1MODE_VBLANK_VLINE_STATUS hardcode parity

Also lands the audit-runs/ analysis notes (.md/.txt/.json digests) for the
iterate 2.x VSync/0x10e8/0x1004 wedge investigation. Raw trace dumps
(.jsonl/.gz/.csv/.stdout) and agent worktrees (.claude/) are gitignored as
regenerable local artifacts — see memory + HANDOFF for the running findings.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

audit-runs/phase-nonmatch-investigation/thread-exits.json

@@ -0,0 +1,23 @@
+{
+  "17": {
+    "event_idx": 4139,
+    "host_ns": 2091816600,
+    "payload": {
+      "exit_code": 0
+    }
+  },
+  "18": {
+    "event_idx": 33084,
+    "host_ns": 2870280100,
+    "payload": {
+      "exit_code": 1
+    }
+  },
+  "26": {
+    "event_idx": 6706,
+    "host_ns": 10280088600,
+    "payload": {
+      "exit_code": 0
+    }
+  }
+}