Rewrite frontend as single self-contained HTML file — all CSS/JS inline, no external files to fail loading

dist/providers/tts/googleCloudTTSProvider.d.ts

@@ -0,0 +1,8 @@
+import { TTSProvider, TTSProviderConfig, TTSOptions, TTSResult } from '../../interfaces';
+export declare class GoogleCloudTTSProvider implements TTSProvider {
+    private config;
+    private client;
+    constructor(config: TTSProviderConfig);
+    textToSpeech(text: string, outputPath: string, options?: TTSOptions): Promise<TTSResult>;
+    private extractLanguageCode;
+}