Fix stats command flow and tracking metrics regressions

- Route default `subminer stats` through attached `--stats`; keep daemon path for `--background`/`--stop`
- Update overview metrics: lookup rate uses lifetime Yomitan lookups per 100 tokens; new words dedupe by headword
- Suppress repeated macOS `Overlay loading...` OSD during fullscreen tracker flaps and improve session-detail chart scaling
- Add/adjust launcher, tracker query, stats server, IPC, overlay, and stats UI regression tests; add changelog fragments

launcher/commands/stats-command.ts

@@ -69,14 +69,11 @@ export async function runStatsCommand(
   try {
     const forwarded = args.statsCleanup
       ? ['--stats', '--stats-response-path', responsePath]
-      : [
-          args.statsStop ? '--stats-daemon-stop' : '--stats-daemon-start',
-          '--stats-response-path',
-          responsePath,
-        ];
-    if (!args.statsCleanup && !args.statsBackground && !args.statsStop) {
-      forwarded.push('--stats-daemon-open-browser');
-    }
+      : args.statsStop
+        ? ['--stats-daemon-stop', '--stats-response-path', responsePath]
+        : args.statsBackground
+          ? ['--stats-daemon-start', '--stats-response-path', responsePath]
+          : ['--stats', '--stats-response-path', responsePath];
     if (args.statsCleanup) {
       forwarded.push('--stats-cleanup');
     }