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.d.ts

@@ -4,6 +4,7 @@ interface ConvertJSONToPDFMessage {
   command: 'convert';
   fileBuffers: ArrayBuffer[];
   fileNames: string[];
+  cpdfUrl?: string;
 }
 
 interface JSONToPDFSuccessResponse {
@@ -17,4 +18,3 @@ interface JSONToPDFErrorResponse {
 }
 
 type JSONToPDFResponse = JSONToPDFSuccessResponse | JSONToPDFErrorResponse;
-