Add module control API, bigcursor with fractional scaling, shared mutex

Module control API:
- Three cdecl exports: WeirdUtils_IsModuleActive, WeirdUtils_DisableModule, WeirdUtils_DisableAll
- C header include/weirdutils_api.h for runtime DLL discovery
- All modules gain pub module_name, isActive(), shared mutex via src/mutex.zig
- build.zig refactored to module_list array of ModuleDesc

Bigcursor:
- D3D9 vtable hooks on SetCursorProperties/ShowCursor
- Scale2x/Scale3x pixel-art upscalers in pure Zig (replaces 12K-line hqx C)
- Bilinear resampler for fractional scales (1.0-4.0, default 1.2)
- Win32 cursor via CreateIconIndirect bypasses D3D9 32x32 limit
- FNV-1a hash cache for ~16 cursor bitmaps
- Lua API: SetCursorScale(n) / GetCursorScale()
- CVar cursorScale for Config.wtf persistence (tenths)

Other:
- Add dpslog module stub
- Docs and README updates

include/weirdutils_api.h

@@ -0,0 +1,82 @@
+/*
+ * weirdutils_api.h - Runtime Module Control API for WeirdUtils
+ *
+ * Header-only, no .lib needed. Include this file and call the inline
+ * wrappers; they resolve the DLL exports at runtime via GetModuleHandleA
+ * and GetProcAddress. Returns 0 / no-ops if WeirdUtils is not loaded.
+ *
+ * Usage:
+ *   #include "weirdutils_api.h"
+ *
+ *   if (WeirdUtils_IsModuleActive("transmogfix"))
+ *       WeirdUtils_DisableModule("transmogfix");
+ */
+
+#ifndef WEIRDUTILS_API_H
+#define WEIRDUTILS_API_H
+
+#include <windows.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* ---- Function pointer typedefs ---- */
+
+typedef int (__cdecl *WeirdUtils_IsModuleActiveFn)(const char *name);
+typedef int (__cdecl *WeirdUtils_DisableModuleFn)(const char *name);
+typedef int (__cdecl *WeirdUtils_DisableAllFn)(void);
+
+/* ---- DLL auto-discovery ---- */
+
+static const char *const WeirdUtils__DllNames[] = {
+    "weirdutils.dll",
+    "worldmarkers.dll",
+    "outline.dll",
+    "interact.dll",
+    "screenshot.dll",
+    "framecrash.dll",
+    "transmogfix.dll",
+    "customassets.dll",
+    "logsessions.dll",
+    "healtextfix.dll",
+    "bigcursor.dll",
+    "minimapicons.dll",
+    "dpslog.dll",
+    NULL
+};
+
+static FARPROC WeirdUtils__Resolve(const char *func_name) {
+    int i;
+    for (i = 0; WeirdUtils__DllNames[i] != NULL; ++i) {
+        HMODULE hMod = GetModuleHandleA(WeirdUtils__DllNames[i]);
+        if (hMod) {
+            FARPROC proc = GetProcAddress(hMod, func_name);
+            if (proc) return proc;
+        }
+    }
+    return NULL;
+}
+
+/* ---- Inline wrappers (no-op if DLL not loaded) ---- */
+
+static int WeirdUtils_IsModuleActive(const char *name) {
+    WeirdUtils_IsModuleActiveFn fn = (WeirdUtils_IsModuleActiveFn)WeirdUtils__Resolve("WeirdUtils_IsModuleActive");
+    return fn ? fn(name) : 0;
+}
+
+static int WeirdUtils_DisableModule(const char *name) {
+    WeirdUtils_DisableModuleFn fn = (WeirdUtils_DisableModuleFn)WeirdUtils__Resolve("WeirdUtils_DisableModule");
+    return fn ? fn(name) : 0;
+}
+
+static int WeirdUtils_DisableAll(void) {
+    WeirdUtils_DisableAllFn fn = (WeirdUtils_DisableAllFn)WeirdUtils__Resolve("WeirdUtils_DisableAll");
+    return fn ? fn() : 0;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* WEIRDUTILS_API_H */