Fix UnmanagedCallersOnly boot crash & Core Engine Improvements (CPU, HLE, AGC) (#81)

* [agc] WAIT_REG_MEM suspend/resume, draw packet fixes, new HLE exports, debug cleanup

Rebased onto upstream 79a7437 (par274/sharpemu, rewritten history).

- GpuWaitRegistry: DCBs suspended on unsatisfied WAIT_REG_MEM are re-polled
  against guest memory on every submit; fixed 64-bit and standard packet parse
  offsets, apply the mask, treat PM4 compare function 0 as "always".
- TryReadSubmittedDrawCount: accept the 5-dword ItDrawIndex2 form emitted by
  DcbDrawIndex (count at +4); menu draws were silently discarded before.
- sceAgcDriverSubmitMultiDcbs: reversed ABI (rdi=address array, rsi=dword
  sizes, rdx=count).
- VideoOut: vblank events, sceVideoOutGetFlipStatus, buffers registered via
  sceVideoOutRegisterBuffers are valid flip targets.
- New HLE: libc stdio (fopen/fread/fseek/ftell/fclose/fgets), Dinkumware
  _Getpctype ctype table, NpTrophy2 stubs, AMPR PAK sequential-read tracker,
  MsgDialog lifecycle, NGS2 alt NIDs + dummy vtable for handle objects,
  guarded memset intrinsic, abort()/strcasecmp null-arg recovery.
- Removed investigation-only code (INT3 breakpoints, qfont/mcpp dumps,
  error-candidate printf traces, unconditional debug logs).

First rendered frame: Quake (PPSA01880) presents a 1920x1080 guest frame.

* Implemented a guarded native intrinsic (rep movsb) in DirectExecutionBackend to bypass HLE dispatch overhead, while preserving memory safety checks.

* [hle] clock_gettime clock ids, AudioOut2 canary fix, NID rebinds, new offline stubs

- clock_gettime (lLMT9vJAck0): support CLOCK_SECOND and the *_PRECISE/*_FAST
  variants instead of returning EINVAL, which games treated as fatal and
  retried in a tight loop.
- AudioOut2: context param writes shrunk to the guest-observed layout (the
  old 0x80-byte reset smashed the stack canary at +0x60 and killed audio
  init); ContextQueryMemory writes the single u64 the caller expects.
- NGS2: dropped wrong alt-NID aliases (they hash to sceImeUpdate,
  sceMouseRead, sceSystemGestureUpdateAllTouchRecognizer - now bound in
  their real libraries); added sceNgs2PanInit; fixed VoiceGetState NIDs.
- New verified stubs: sceUltInitialize, sceNpUniversalDataSystemDestroyHandle,
  sceNpGetOnlineId, sceNpGetNpReachabilityState, sceImeKeyboardOpen,
  sceImeKeyboardGetResourceId, sceMouseOpen, sceKernelAprGetFileSize.
- Import gateway: unwind guest workers at dispatch during backend teardown;
  env-gated SHARPEMU_LOG_THREAD_MODE tracing.

* [cpu] Isolate guest execution on native worker threads

Guest entry stubs no longer run above CLR-managed frames: each run is handed
to a pooled raw OS thread whose loop is emitted native code. While guest code
executes there is not a single managed frame on the thread and it stays in
preemptive GC mode, so the GC never walks a frame chain interleaved with
guest stubs that carry no CLR unwind info (the ReversePInvokeBadTransition /
UnmanagedCallersOnly FailFast class of crashes on pumped guest threads).

- NativeGuestExecutor: CreateThread + emitted run loop (WaitForSingleObject,
  UnmanagedCallersOnly prologue/epilogue, entry stub call, SetEvent). The
  prologue rebinds guest TLS, the host-RSP slot, thread affinity and the
  Active* ambient per run, so workers carry no guest identity and pool
  freely; the orchestrating managed thread parks in a preemptive wait.
- All three entry sites route through RunGuestEntryStub: guest thread
  entries, blocked-continuation resumes, and the main ExecuteEntry.
- Teardown stops workers before any executable stub or TLS index they
  reference is freed; a worker that will not stop leaks its loop instead of
  freeing running code.
- Kill switch: SHARPEMU_DISABLE_NATIVE_GUEST_WORKERS=1 restores the inline
  calli path.

src/SharpEmu.Libs/Ime/ImeExports.cs

@@ -0,0 +1,46 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using SharpEmu.HLE;
+
+namespace SharpEmu.Libs.Ime;
+
+public static class ImeExports
+{
+    // Quake (KEX) calls this from its main loop and from the audio bring-up path with
+    // an event-handler pointer. No IME session ever exists here, so report success
+    // without invoking the handler ("no pending IME events"). This NID was previously
+    // misbound as an sceNgs2VoiceControl alias, which fed the game NGS2 errors.
+    [SysAbiExport(
+        Nid = "-4GCfYdNF1s",
+        ExportName = "sceImeUpdate",
+        Target = Generation.Gen4 | Generation.Gen5,
+        LibraryName = "libSceIme")]
+    public static int ImeUpdate(CpuContext ctx)
+    {
+        ctx[CpuRegister.Rax] = 0;
+        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
+    }
+
+    [SysAbiExport(
+        Nid = "eaFXjfJv3xs",
+        ExportName = "sceImeKeyboardOpen",
+        Target = Generation.Gen4 | Generation.Gen5,
+        LibraryName = "libSceIme")]
+    public static int ImeKeyboardOpen(CpuContext ctx)
+    {
+        ctx[CpuRegister.Rax] = 0;
+        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
+    }
+
+    [SysAbiExport(
+        Nid = "dKadqZFgKKQ",
+        ExportName = "sceImeKeyboardGetResourceId",
+        Target = Generation.Gen4 | Generation.Gen5,
+        LibraryName = "libSceIme")]
+    public static int ImeKeyboardGetResourceId(CpuContext ctx)
+    {
+        ctx[CpuRegister.Rax] = 0;
+        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
+    }
+}