Fix SWELL drag guard, channel-fork the VST editor window class, dedupe own-module match

Panel drag no longer misfires on SWELL's always-zero wParam; stable/beta VST editors register distinct window classes against their own module instead of colliding on REAPER's; own-module basename matching moves to a tested pure helper.

tests/test_window_origin.cpp

@@ -173,6 +173,27 @@ static void testUnknownAndEmptyChainsAreNotPlugin() {
     CHECK(!isPluginEditorChain({}));
 }
 
+// --- isOwnModulePath -----------------------------------------------------------
+
+static void testOwnModulePathCaseFolds() {
+    CHECK(isOwnModulePath("C:\\VST3\\reasampler_9000.vst3", "reasampler_9000.vst3"));
+    CHECK(isOwnModulePath("C:\\VST3\\ReaSampler_9000.VST3", "reasampler_9000.vst3"));
+}
+
+static void testOwnModulePathBundlePathForwardAndBackSlash() {
+    CHECK(isOwnModulePath(
+        "C:\\VST3\\reasampler_9000.vst3\\Contents\\x86_64-win\\reasampler_9000.vst3",
+        "reasampler_9000.vst3"));
+    CHECK(isOwnModulePath(
+        "C:/VST3/reasampler_9000.vst3/Contents/x86_64-win/reasampler_9000.vst3",
+        "reasampler_9000.vst3"));
+}
+
+static void testOwnModulePathStableAndBetaDoNotMatchEachOther() {
+    CHECK(!isOwnModulePath("C:\\VST3\\reasampler_9000_beta.vst3", "reasampler_9000.vst3"));
+    CHECK(!isOwnModulePath("C:\\VST3\\reasampler_9000.vst3", "reasampler_9000_beta.vst3"));
+}
+
 int main() {
     testHostExecutableIsHost();
     testOsModulesAreSystem();
@@ -192,6 +213,10 @@ int main() {
     testOtherPluginBesideOwnInstrumentIsStillPlugin();
     testUnknownAndEmptyChainsAreNotPlugin();
 
+    testOwnModulePathCaseFolds();
+    testOwnModulePathBundlePathForwardAndBackSlash();
+    testOwnModulePathStableAndBetaDoNotMatchEachOther();
+
     if (g_fail == 0) std::printf("All tests passed.\n");
     return g_fail ? 1 : 0;
 }