fix(flowchart): expose pure modules as window globals for standalone window; v4.9.7

Each pure module's UMD wrapper assigned window.FlowchartXxx only in the else branch — when 'module' was undefined. But the renderer runs with nodeIntegration:true, so 'module' is always truthy and the else branch never ran. The standalone Flowchart Generator window then aborted with 'Flowchart pure modules not loaded'.

Fix: append 'if (typeof window !== undefined) window.FlowchartXxx = exported;' after the CommonJS branch in all 4 pure modules (store, shapes, mermaid, canvas). Both branches can run now; the legacy sidebar panel still loads them via require() and the renderer unconditionally exposes the global.

Regression guard: 4 new source-grep tests in tests/flowchart-controller.test.js assert each module's source contains the 'window.FlowchartXxx = exported' assignment.

Attribution: Amit Haridas

package.json

@@ -1,6 +1,6 @@
 {
   "name": "markdown-converter",
-  "version": "4.9.6",
+  "version": "4.9.7",
   "description": "Professional Markdown editor and universal file converter with PDF editing, batch processing, and syntax highlighting",
   "main": "src/main.js",
   "scripts": {