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

stats/src/components/sessions/SessionRow.tsx

@@ -58,6 +58,7 @@ export function SessionRow({
   deleteDisabled = false,
 }: SessionRowProps) {
   const displayWordCount = getSessionDisplayWordCount(session);
+  const knownWordsSeen = session.knownWordsSeen;
 
   return (
     <div className="relative group">
@@ -95,6 +96,12 @@ export function SessionRow({
             </div>
             <div className="text-ctp-overlay2">tokens</div>
           </div>
+          <div>
+            <div className="text-ctp-green font-medium font-mono tabular-nums">
+              {formatNumber(knownWordsSeen)}
+            </div>
+            <div className="text-ctp-overlay2">known words</div>
+          </div>
         </div>
         <div
           className={`text-ctp-blue text-xs transition-transform ${isExpanded ? 'rotate-90' : ''}`}