add app control server for launcher-to-app attachment

- Launcher detects a running app via control socket and attaches without spawning a new process
- Own-lifecycle app launches now pass --background --managed-playback; borrowed apps skip --background
- Separate plain subtitle websocket (tokens: []) from annotation websocket
- Default pauseVideoOnHover to true; update docs and config.example.jsonc
- Setup: remove plugin readiness card, add Open SubMiner Settings button

src/main/runtime/app-control-server.ts

@@ -0,0 +1,96 @@
+import fs from 'node:fs';
+import net from 'node:net';
+import path from 'node:path';
+import {
+  encodeAppControlResponse,
+  parseAppControlRequestLine,
+  type AppControlResponse,
+} from '../../shared/app-control';
+
+export interface AppControlServerOptions {
+  socketPath: string;
+  platform?: NodeJS.Platform;
+  handleArgv: (argv: string[]) => void;
+  logDebug?: (message: string) => void;
+  logWarn?: (message: string, error?: unknown) => void;
+}
+
+export interface AppControlServerHandle {
+  close: () => void;
+}
+
+function prepareSocketPath(socketPath: string, platform: NodeJS.Platform): void {
+  if (platform === 'win32') return;
+  fs.mkdirSync(path.dirname(socketPath), { recursive: true });
+  fs.rmSync(socketPath, { force: true });
+}
+
+function cleanupSocketPath(socketPath: string, platform: NodeJS.Platform): void {
+  if (platform === 'win32') return;
+  try {
+    fs.rmSync(socketPath, { force: true });
+  } catch {
+    // ignore
+  }
+}
+
+function writeResponse(socket: net.Socket, response: AppControlResponse): void {
+  socket.end(encodeAppControlResponse(response));
+}
+
+export function startAppControlServer(options: AppControlServerOptions): AppControlServerHandle {
+  const platform = options.platform ?? process.platform;
+  prepareSocketPath(options.socketPath, platform);
+
+  const server = net.createServer((socket) => {
+    let buffer = '';
+    let handled = false;
+
+    socket.on('data', (chunk) => {
+      if (handled) return;
+      buffer += chunk.toString('utf8');
+      if (buffer.length > 65536) {
+        handled = true;
+        writeResponse(socket, { ok: false, error: 'App control request too large' });
+        return;
+      }
+
+      const newlineIndex = buffer.indexOf('\n');
+      if (newlineIndex < 0) return;
+      handled = true;
+
+      try {
+        const request = parseAppControlRequestLine(buffer.slice(0, newlineIndex));
+        options.handleArgv(request.argv);
+        writeResponse(socket, { ok: true });
+      } catch (error) {
+        options.logWarn?.('Failed to handle app control command.', error);
+        writeResponse(socket, {
+          ok: false,
+          error: error instanceof Error ? error.message : String(error),
+        });
+      }
+    });
+  });
+
+  server.on('error', (error) => {
+    options.logWarn?.(`App control socket failed: ${options.socketPath}`, error);
+  });
+  server.listen(options.socketPath, () => {
+    options.logDebug?.(`App control socket listening: ${options.socketPath}`);
+  });
+
+  let closed = false;
+  return {
+    close: () => {
+      if (closed) return;
+      closed = true;
+      try {
+        server.close();
+      } catch {
+        // ignore
+      }
+      cleanupSocketPath(options.socketPath, platform);
+    },
+  };
+}