Decouple stats daemon and preserve final mine OSD status

- Run `subminer stats -b` as a dedicated daemon process, independent from the overlay app
- Stop Anki progress spinner before showing final `✓`/`x` mine result so it is not overwritten
- Keep grammar/noise subtitle tokens hoverable while stripping annotation metadata

src/stats-daemon-control.ts

@@ -0,0 +1,102 @@
+import type { BackgroundStatsServerState } from './main/runtime/stats-daemon';
+import type { StatsCliCommandResponse } from './main/runtime/stats-cli-command';
+
+export type StatsDaemonControlAction = 'start' | 'stop';
+
+export type StatsDaemonControlArgs = {
+  action: StatsDaemonControlAction;
+  responsePath?: string;
+  openBrowser: boolean;
+  daemonScriptPath: string;
+  userDataPath: string;
+};
+
+type SpawnStatsDaemonOptions = {
+  scriptPath: string;
+  responsePath?: string;
+  userDataPath: string;
+};
+
+export function createRunStatsDaemonControlHandler(deps: {
+  statePath: string;
+  readState: () => BackgroundStatsServerState | null;
+  removeState: () => void;
+  isProcessAlive: (pid: number) => boolean;
+  resolveUrl: (state: Pick<BackgroundStatsServerState, 'port'>) => string;
+  spawnDaemon: (options: SpawnStatsDaemonOptions) => Promise<number> | number;
+  waitForDaemonResponse: (responsePath: string) => Promise<StatsCliCommandResponse>;
+  openExternal: (url: string) => Promise<unknown>;
+  writeResponse: (responsePath: string, payload: StatsCliCommandResponse) => void;
+  killProcess: (pid: number, signal: NodeJS.Signals) => void;
+  sleep: (ms: number) => Promise<void>;
+}) {
+  const writeResponseSafe = (
+    responsePath: string | undefined,
+    payload: StatsCliCommandResponse,
+  ): void => {
+    if (!responsePath) return;
+    deps.writeResponse(responsePath, payload);
+  };
+
+  return async (args: StatsDaemonControlArgs): Promise<number> => {
+    if (args.action === 'start') {
+      const state = deps.readState();
+      if (state) {
+        if (deps.isProcessAlive(state.pid)) {
+          const url = deps.resolveUrl(state);
+          writeResponseSafe(args.responsePath, { ok: true, url });
+          if (args.openBrowser) {
+            await deps.openExternal(url);
+          }
+          return 0;
+        }
+        deps.removeState();
+      }
+
+      if (!args.responsePath) {
+        throw new Error('Missing --stats-response-path for stats daemon start.');
+      }
+
+      await deps.spawnDaemon({
+        scriptPath: args.daemonScriptPath,
+        responsePath: args.responsePath,
+        userDataPath: args.userDataPath,
+      });
+      const response = await deps.waitForDaemonResponse(args.responsePath);
+      if (response.ok && args.openBrowser && response.url) {
+        await deps.openExternal(response.url);
+      }
+      return response.ok ? 0 : 1;
+    }
+
+    const state = deps.readState();
+    if (!state) {
+      deps.removeState();
+      writeResponseSafe(args.responsePath, { ok: true });
+      return 0;
+    }
+
+    if (!deps.isProcessAlive(state.pid)) {
+      deps.removeState();
+      writeResponseSafe(args.responsePath, { ok: true });
+      return 0;
+    }
+
+    deps.killProcess(state.pid, 'SIGTERM');
+    const deadline = Date.now() + 2_000;
+    while (Date.now() < deadline) {
+      if (!deps.isProcessAlive(state.pid)) {
+        deps.removeState();
+        writeResponseSafe(args.responsePath, { ok: true });
+        return 0;
+      }
+      await deps.sleep(50);
+    }
+
+    writeResponseSafe(args.responsePath, {
+      ok: false,
+      error: 'Timed out stopping background stats server.',
+    });
+    return 1;
+  };
+}