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/review-a-step2-natural-trigger/ours_signal_counts.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+"""Count signal events on each tid in ours-postfix.jsonl during the full
+run window. Compare against canary [1.9..2.1s]."""
+import json
+from collections import Counter
+
+OURS = "/home/fabi/RE - Project Sylpheed/xenia-rs/audit-runs/phase-w-wedge-reattack/ours-postfix.jsonl"
+counts = Counter()
+last_ns_per_tid = {}
+first_ns_per_tid = {}
+event_count_per_tid = Counter()
+
+with open(OURS, "r") as f:
+    for line in f:
+        try:
+            ev = json.loads(line)
+        except json.JSONDecodeError:
+            continue
+        tid = ev.get("tid")
+        if tid is None:
+            continue
+        host_ns = ev.get("host_ns", 0)
+        event_count_per_tid[tid] += 1
+        if tid not in first_ns_per_tid:
+            first_ns_per_tid[tid] = host_ns
+        last_ns_per_tid[tid] = host_ns
+        kind = ev.get("kind", "")
+        if kind == "kernel.call":
+            n = ev["payload"].get("name", "")
+            if n in ("NtSetEvent", "NtReleaseSemaphore", "NtSetEventBoostPriority", "KeSetEvent"):
+                counts[(tid, n)] += 1
+
+print("=== Signal counts in ours-postfix.jsonl (full window ~1.73s wallclock) ===")
+total = 0
+for (tid, n), c in sorted(counts.items()):
+    print(f"  tid={tid:3d}  {n:30s}  {c}")
+    total += c
+print(f"  TOTAL signals: {total}")
+
+print("\n=== Per-tid event counts + lifetime ===")
+for tid in sorted(event_count_per_tid):
+    first = first_ns_per_tid.get(tid, 0) / 1e9
+    last = last_ns_per_tid.get(tid, 0) / 1e9
+    print(f"  tid={tid:3d}  {event_count_per_tid[tid]:7d} events  first={first:.4f}s last={last:.4f}s")