[AGC] Quake rendering progress: WAIT_REG_MEM, draw fixes, VideoOut, and HLE improvements (#68)

* [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.

src/SharpEmu.Libs/UserService/UserServiceExports.cs

@@ -18,6 +18,9 @@ public static class UserServiceExports
     private const string PrimaryUserName = "SharpEmu";
     private static int _loginEventDelivered;
 
+    private static readonly bool _traceUserService =
+        string.Equals(Environment.GetEnvironmentVariable("SHARPEMU_LOG_USER_SERVICE"), "1", StringComparison.Ordinal);
+
     [SysAbiExport(
         Nid = "j3YMu1MVNNo",
         ExportName = "sceUserServiceInitialize",
@@ -42,9 +45,11 @@ public static class UserServiceExports
             return ctx.SetReturn(OrbisUserServiceErrorInvalidArgument);
         }
 
-        return ctx.TryWriteInt32(userIdAddress, PrimaryUserId)
-            ? ctx.SetReturn(0)
-            : ctx.SetReturn((int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
+        var result = ctx.TryWriteInt32(userIdAddress, PrimaryUserId)
+            ? 0
+            : (int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT;
+        TraceUserService($"get_initial_user out=0x{userIdAddress:X16} value={PrimaryUserId} result=0x{result:X8}");
+        return ctx.SetReturn(result);
     }
 
     [SysAbiExport(
@@ -124,9 +129,12 @@ public static class UserServiceExports
 
         Span<byte> output = stackalloc byte[nameBytes.Length + 1];
         nameBytes.CopyTo(output);
-        return ctx.Memory.TryWrite(nameAddress, output)
-            ? ctx.SetReturn(0)
-            : ctx.SetReturn((int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
+        var result = ctx.Memory.TryWrite(nameAddress, output)
+            ? 0
+            : (int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT;
+        TraceUserService(
+            $"get_user_name user={userId} out=0x{nameAddress:X16} capacity=0x{capacity:X} value='{PrimaryUserName}' result=0x{result:X8}");
+        return ctx.SetReturn(result);
     }
 
     [SysAbiExport(
@@ -152,4 +160,12 @@ public static class UserServiceExports
             ? ctx.SetReturn(0)
             : ctx.SetReturn((int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
     }
+
+    private static void TraceUserService(string message)
+    {
+        if (_traceUserService)
+        {
+            Console.Error.WriteLine($"[LOADER][TRACE] user_service.{message}");
+        }
+    }
 }