Fix FreeRDP crash: echo VERSION param + upgrade guacd to latest

- rdp.ts: dynamically acknowledge guacd's VERSION_x_y_z parameter by
  echoing it back in the connect instruction. Without this, guacd 1.5+
  runs in legacy mode which crashes FreeRDP on modern Windows targets.
  Also add disable-glyph-caching and resize-method params.
- docker-compose: upgrade guacd from 1.5.4 to latest to get FreeRDP 3.x
  which fixes known crash bugs with Windows 11 22H2+ / Server 2022

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/websocket/rdp.ts

@@ -157,8 +157,19 @@ export async function rdpWebsocket(fastify: FastifyInstance) {
           'enable-drive': 'false',
           'create-drive-path': 'false',
           'enable-printing': 'false',
+          'disable-glyph-caching': 'true',
+          'resize-method': 'display-update',
         };
 
+        // Acknowledge whichever VERSION_x_y_z guacd advertises.
+        // Without this echo, guacd runs in legacy compatibility mode which
+        // can cause FreeRDP to crash on modern Windows targets.
+        for (const name of argNames) {
+          if (name.startsWith('VERSION_')) {
+            rdpParams[name] = name;
+          }
+        }
+
         // 3. Connect with values guacd requested
         const argValues = argNames.map((name) => rdpParams[name] ?? '');
         guacd.write(buildInstruction('connect', ...argValues));