[Audit] round 24: signal-path probes (XEvent::Set + IO + NtDuplicateObject)

Adds AUDIT-HLC probes for every path that signals an XEvent or duplicates
its handle, so the round-23 puzzle (waits completing without visible
NtSetEvent/KeSetEvent) can be cross-referenced by underlying X_KEVENT VA
and by primary handle.

  * NtCreateEvent_inner: always log kevent_va for handle/VA cross-ref
  * XEvent::Set: universal hook prints primary handle + kevent_va + LR;
    catches all paths into the event regardless of shim used
  * NtSetEvent: extended with PPC back-chain walk for caller's guest_lr
    (same idiom as the wait probe), so the signaler function is
    immediately identifiable
  * NtReadFile / NtReadFileScatter / NtWriteFile: log when signal_event
    path fires ev->Set() inline at IO completion (bypasses both
    NtSetEvent and KeSetEvent shims)
  * CompleteOverlappedEx (kernel_state.cc): log when overlapped event
    is signaled at completion
  * NtDuplicateObject: log src/dst handle pair (round-24 confirmed silph
    event is dup'd before signaling, explaining the handle-mismatch
    puzzle between NtSetEvent's `handle=` argument and XEvent::Set's
    primary handle())

Result: silph wait at sub_821CB030+0x1B0 on handle F80000A0 is signaled
via NtSetEvent on handle F80000A8 (the duplicate created by sub_8245D9D8
at lr=0x82450DF4 inside the worker chain sub_82450A28 ← 0xA68 ← 0xB68).
Verdict A confirmed: signaler exists and is reachable, but round-17.β
missed it because the search keyed on the wrong handle. No bypass path;
the worker chain is identical between canary and ours-impl, but ours
signals different handles (work-item queue divergence at sub_82452DC0).

Audit-only diagnostic. No semantic changes. Net delta +86 LOC across 7
files. All probes gated on the existing audit_handle_lifecycle cvar
(default off). Tested via Sylpheed boot (35 s, 4 MB log). Audit-handle-
lifecycle-probes branch, local-only.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/xenia/kernel/xboxkrnl/xboxkrnl_ob.cc

@@ -10,6 +10,8 @@
 #include "xenia/kernel/xboxkrnl/xboxkrnl_ob.h"
 #include "xenia/base/logging.h"
 #include "xenia/cpu/processor.h"
+#include "xenia/cpu/thread_state.h"
+#include "xenia/kernel/kernel_flags.h"
 #include "xenia/kernel/kernel_state.h"
 #include "xenia/kernel/xboxkrnl/xboxkrnl_private.h"
 #include "xenia/kernel/xboxkrnl/xboxkrnl_threading.h"
@@ -398,6 +400,14 @@ dword_result_t NtDuplicateObject_entry(dword_t handle, lpdword_t new_handle_ptr,
   X_STATUS result =
       kernel_state()->object_table()->DuplicateHandle(handle, &new_handle);
 
+  if (cvars::audit_handle_lifecycle) {
+    uint32_t lr = static_cast<uint32_t>(cpu::ThreadState::Get()->context()->lr);
+    XELOGKERNEL(
+        "AUDIT-HLC NtDuplicateObject src={:08X} dst={:08X} options={:08X} "
+        "lr={:08X}",
+        uint32_t(handle), uint32_t(new_handle), uint32_t(options), lr);
+  }
+
   if (new_handle_ptr) {
     *new_handle_ptr = new_handle;
   }