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>

crates/xenia-gpu/src/mmio_region.rs

@@ -56,7 +56,15 @@ pub fn build_region(mmio: &GpuMmio) -> MmioRegion {
                 // — serve the last-written value.
                 reg::CP_INT_ACK => read_int_ack.load(Ordering::Relaxed),
                 reg::D1MODE_VBLANK_VLINE_STATUS => {
-                    read_vblank_status.load(Ordering::Relaxed)
+                    // 2.AO: hardcode to 1 to match canary
+                    // (`graphics_system.cc:309-310`). The guest VSync
+                    // callback (`sub_824BE9A0` @ PC 0x824BEA38-0x824BEA44)
+                    // reads bit 0 to decide whether vblank fired; if the
+                    // first delivery precedes `tick_vsync_instr`'s first
+                    // bit-set the callback silently no-ops. Canary returns
+                    // 1 unconditionally; we mirror that.
+                    let _ = &read_vblank_status; // keep clone alive
+                    1
                 }
                 _ => {
                     tracing::trace!(