feat: node property inspector

- Right-click node -> Properties shows details dialog
- Shows: ID, name, class, volume, ports, sample rate, channels,
  format, quantum, rate, device, bus, API, priority
- Backend parses extra PipeWire node props (clock.rate, channels, etc.)
- Node type includes all new fields
- stop() already had the SSE cleanup fix

src/web_server.cpp

@@ -111,6 +111,15 @@ std::string WebServer::buildGraphJson() const {
              << ",\"node_type\":\"" << nodeTypeStr(n.node_type) << "\""
              << ",\"volume\":" << n.volume
              << ",\"mute\":" << (n.mute ? "true" : "false")
+             << ",\"sample_rate\":" << n.sample_rate
+             << ",\"channels\":" << n.channels
+             << ",\"quantum\":" << n.quantum
+             << ",\"rate\":" << n.rate
+             << ",\"format\":\"" << escapeJson(n.format) << "\""
+             << ",\"device_name\":\"" << escapeJson(n.device_name) << "\""
+             << ",\"device_bus\":\"" << escapeJson(n.device_bus) << "\""
+             << ",\"api\":\"" << escapeJson(n.api) << "\""
+             << ",\"priority\":" << n.priority
              << ",\"port_ids\":[";
         bool first_p = true;
         for (uint32_t pid : n.port_ids) {