vgpu in-guest producer in-tree, release CI, flexible vmie discovery

- src/si/vgpu-stream: in-guest vgpu producer built as a Windows cross-compiled target (if(WIN32))
- .gitea: release workflow — cross-build the agent and build/publish the deb against system vmie
- cmake/makefile: resolve vmie from a source tree (LIBVMIE_PATH) or installed libvmie-dev

src/si/vgpu-stream/win32/geometry.c

@@ -0,0 +1,52 @@
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include "geometry.h"
+#include "stream.h"        /* vgpu_publish_geometry */
+
+/* GetDpiForMonitor lives in Shcore.dll (per-monitor DPI awareness API). Loaded dynamically so
+ * the binary does not hard-depend on it; absence degrades dpi to "unknown" (0). */
+typedef HRESULT (WINAPI *GetDpiForMonitor_t)(HMONITOR, int /*MDT_*/, UINT*, UINT*);
+#define VGPU_MDT_EFFECTIVE_DPI 0
+
+static UINT monitor_dpi(HMONITOR mon) {
+    static GetDpiForMonitor_t fn = NULL;
+    static int tried = 0;
+    if (!tried) {
+        HMODULE lib = LoadLibraryA("Shcore.dll");
+        if (lib) fn = (GetDpiForMonitor_t)(void*)GetProcAddress(lib, "GetDpiForMonitor");
+        tried = 1;
+    }
+    if (!fn || !mon) return 0u;
+    UINT dx = 0, dy = 0;
+    if (fn(mon, VGPU_MDT_EFFECTIVE_DPI, &dx, &dy) != S_OK || dx == 0u)
+        return 0u;
+    return dx;
+}
+
+static uint32_t monitor_refresh_mhz(HMONITOR mon) {
+    MONITORINFOEXW mi; mi.cbSize = sizeof mi;
+    if (!mon || !GetMonitorInfoW(mon, (MONITORINFO*)&mi))
+        return 0u;
+    DEVMODEW dm; ZeroMemory(&dm, sizeof dm); dm.dmSize = sizeof dm;
+    if (!EnumDisplaySettingsW(mi.szDevice, ENUM_CURRENT_SETTINGS, &dm))
+        return 0u;
+    if (dm.dmDisplayFrequency <= 1u)   /* 0/1 = hardware default, not a real rate */
+        return 0u;
+    return (uint32_t)dm.dmDisplayFrequency * 1000u;   /* whole Hz -> milli-Hz */
+}
+
+void geometry_sample_and_publish(vgpu_ctx* ctx, int32_t cap_x, int32_t cap_y) {
+    int32_t virt_x = (int32_t)GetSystemMetrics(SM_XVIRTUALSCREEN);
+    int32_t virt_y = (int32_t)GetSystemMetrics(SM_YVIRTUALSCREEN);
+    uint32_t virt_w = (uint32_t)GetSystemMetrics(SM_CXVIRTUALSCREEN);
+    uint32_t virt_h = (uint32_t)GetSystemMetrics(SM_CYVIRTUALSCREEN);
+
+    POINT origin = { cap_x, cap_y };
+    HMONITOR mon = MonitorFromPoint(origin, MONITOR_DEFAULTTOPRIMARY);
+
+    uint32_t dpi     = monitor_dpi(mon);
+    uint32_t refresh = monitor_refresh_mhz(mon);
+
+    vgpu_publish_geometry(&ctx->view, virt_x, virt_y, virt_w, virt_h,
+                          cap_x, cap_y, dpi, refresh);
+}