feat: separate AGPL libraries and add dynamic WASM loading

- Add WASM settings page for configuring external AGPL modules
- Implement dynamic loading for PyMuPDF, Ghostscript, and CoherentPDF
- Add Cloudflare Worker proxy for serving WASM files with CORS
- Update all affected tool pages to check WASM availability
- Add showWasmRequiredDialog for missing module configuration

Documentation:
- Update README, licensing.html, and docs to clarify AGPL components
  are not bundled and must be configured separately
- Add WASM-PROXY.md deployment guide with recommended source URLs
- Rename "CPDF" to "CoherentPDF" for consistency

public/workers/json-to-pdf.worker.js

@@ -1,5 +1,24 @@
-const baseUrl = self.location.href.substring(0, self.location.href.lastIndexOf('/workers/') + 1);
-self.importScripts(baseUrl + 'coherentpdf.browser.min.js');
+let cpdfLoaded = false;
+
+function loadCpdf(cpdfUrl) {
+  if (cpdfLoaded) return Promise.resolve();
+
+  return new Promise((resolve, reject) => {
+    if (typeof coherentpdf !== 'undefined') {
+      cpdfLoaded = true;
+      resolve();
+      return;
+    }
+
+    try {
+      self.importScripts(cpdfUrl);
+      cpdfLoaded = true;
+      resolve();
+    } catch (error) {
+      reject(new Error('Failed to load CoherentPDF: ' + error.message));
+    }
+  });
+}
 
 function convertJSONsToPDFInWorker(fileBuffers, fileNames) {
   try {
@@ -15,13 +34,12 @@ function convertJSONsToPDFInWorker(fileBuffers, fileNames) {
       try {
         pdf = coherentpdf.fromJSONMemory(uint8Array);
       } catch (error) {
-        const errorMsg = error && error.message
-          ? error.message
-          : 'Unknown error';
+        const errorMsg =
+          error && error.message ? error.message : 'Unknown error';
         throw new Error(
           `Failed to convert "${fileName}" to PDF. ` +
-          `The JSON file must be in the format produced by cpdf's outputJSONMemory. ` +
-          `Error: ${errorMsg}`
+            `The JSON file must be in the format produced by cpdf's outputJSONMemory. ` +
+            `Error: ${errorMsg}`
         );
       }
 
@@ -56,9 +74,29 @@ function convertJSONsToPDFInWorker(fileBuffers, fileNames) {
   }
 }
 
-self.onmessage = (e) => {
+self.onmessage = async function (e) {
+  const { cpdfUrl } = e.data;
+
+  if (!cpdfUrl) {
+    self.postMessage({
+      status: 'error',
+      message:
+        'CoherentPDF URL not provided. Please configure it in WASM Settings.',
+    });
+    return;
+  }
+
+  try {
+    await loadCpdf(cpdfUrl);
+  } catch (error) {
+    self.postMessage({
+      status: 'error',
+      message: error.message,
+    });
+    return;
+  }
+
   if (e.data.command === 'convert') {
     convertJSONsToPDFInWorker(e.data.fileBuffers, e.data.fileNames);
   }
 };
-