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.

src/core/ui/window_origin.cpp

@@ -46,4 +46,17 @@ bool isPluginEditorChain(const std::vector<WindowCode>& chain) {
     return std::find(chain.begin(), chain.end(), WindowCode::Plugin) != chain.end();
 }
 
+bool isOwnModulePath(const std::string& path, const std::string& ownName) {
+    const std::size_t pos = path.find_last_of("\\/");
+    const std::string base = pos == std::string::npos ? path : path.substr(pos + 1);
+    if (base.size() != ownName.size()) return false;
+    for (std::size_t i = 0; i < base.size(); ++i) {
+        char a = base[i], b = ownName[i];
+        if (a >= 'A' && a <= 'Z') a = static_cast<char>(a - 'A' + 'a');
+        if (b >= 'A' && b <= 'Z') b = static_cast<char>(b - 'A' + 'a');
+        if (a != b) return false;
+    }
+    return true;
+}
+
 }  // namespace reasampler::ui

src/core/ui/window_origin.h

@@ -24,10 +24,8 @@ struct WindowFacts {
     bool otherProcess = false;  // the window belongs to a process other than the host's
     bool procResolved = false;  // the class procedure lies inside a loaded module
     bool hostModule = false;    // ...and that module is the host executable
-    // ...and that module is THIS channel's ReaSampler 9000 .vst3 (basename match, set by the
-    // shell against app_version::vstOutputName() + ".vst3" — stable and beta each recognise only
-    // their own binary, never the other channel's). A drag over our own instrument's editor is
-    // the load-bearing-principle instrument-drop outcome, not the OS hand-off other plugins get.
+    // ...and that module is THIS channel's ReaSampler 9000 .vst3. Rationale: core/ui/CLAUDE.md's
+    // window_origin entry (the ownModule/Instrument exemption).
     bool ownModule = false;
     std::string modulePath;     // that module's file path, UTF-8
 };
@@ -43,4 +41,9 @@ WindowCode classifyWindowCode(const WindowFacts& facts, const std::string& syste
 // proof — the hand-off this gates is modal, so it needs positive evidence.
 bool isPluginEditorChain(const std::vector<WindowCode>& chain);
 
+// True iff `path`'s file name (the part after the last separator, forward or back) matches
+// `ownName` case-insensitively — see WindowFacts::ownModule for why this decides Instrument vs
+// Plugin. `path` may be a bundle path (only the final component is compared).
+bool isOwnModulePath(const std::string& path, const std::string& ownName);
+
 }  // namespace reasampler::ui