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/lib/dashboard-data.test.ts

@@ -35,6 +35,8 @@ test('buildOverviewSummary aggregates tracked totals and recent windows', () =>
       lookupCount: 10,
       lookupHits: 8,
       yomitanLookupCount: 0,
+      knownWordsSeen: 10,
+      knownWordRate: 12.5,
     },
   ];
   const rollups: DailyRollup[] = [
@@ -66,6 +68,8 @@ test('buildOverviewSummary aggregates tracked totals and recent windows', () =>
       totalCards: 9,
       totalLookupCount: 100,
       totalLookupHits: 80,
+      totalTokensSeen: 1000,
+      totalYomitanLookupCount: 23,
       newWordsToday: 5,
       newWordsThisWeek: 20,
     },
@@ -80,7 +84,10 @@ test('buildOverviewSummary aggregates tracked totals and recent windows', () =>
   assert.equal(summary.allTimeMinutes, 50);
   assert.equal(summary.activeDays, 2);
   assert.equal(summary.totalSessions, 15);
-  assert.equal(summary.lookupRate, 80);
+  assert.deepEqual(summary.lookupRate, {
+    shortValue: '2.3 / 100 tokens',
+    longValue: '2.3 lookups per 100 tokens',
+  });
 });
 
 test('buildOverviewSummary prefers lifetime totals from hints when provided', () => {
@@ -104,6 +111,8 @@ test('buildOverviewSummary prefers lifetime totals from hints when provided', ()
         lookupCount: 1,
         lookupHits: 1,
         yomitanLookupCount: 0,
+        knownWordsSeen: 2,
+        knownWordRate: 20,
       },
     ],
     rollups: [
@@ -132,6 +141,8 @@ test('buildOverviewSummary prefers lifetime totals from hints when provided', ()
       totalCards: 5,
       totalLookupCount: 0,
       totalLookupHits: 0,
+      totalTokensSeen: 0,
+      totalYomitanLookupCount: 0,
       newWordsToday: 0,
       newWordsThisWeek: 0,
     },
@@ -141,6 +152,7 @@ test('buildOverviewSummary prefers lifetime totals from hints when provided', ()
   assert.equal(summary.totalTrackedCards, 5);
   assert.equal(summary.allTimeMinutes, 120);
   assert.equal(summary.activeDays, 40);
+  assert.equal(summary.lookupRate, null);
 });
 
 test('buildVocabularySummary treats firstSeen timestamps as seconds', () => {

stats/src/lib/dashboard-data.ts

@@ -6,6 +6,7 @@ import type {
   VocabularyEntry,
 } from '../types/stats';
 import { epochDayToDate, epochMsFromDbTimestamp, localDayFromMs } from './formatters';
+import { buildLookupRateDisplay, type LookupRateDisplay } from './yomitan-lookup';
 
 export interface ChartPoint {
   label: string;
@@ -25,7 +26,7 @@ export interface OverviewSummary {
   averageSessionMinutes: number;
   activeDays: number;
   totalSessions: number;
-  lookupRate: number | null;
+  lookupRate: LookupRateDisplay | null;
   todayTokens: number;
   newWordsToday: number;
   newWordsThisWeek: number;
@@ -181,10 +182,10 @@ export function buildOverviewSummary(
         : 0,
     activeDays: overview.hints.activeDays ?? daysWithActivity.size,
     totalSessions: overview.hints.totalSessions ?? overview.sessions.length,
-    lookupRate:
-      overview.hints.totalLookupCount > 0
-        ? Math.round((overview.hints.totalLookupHits / overview.hints.totalLookupCount) * 100)
-        : null,
+    lookupRate: buildLookupRateDisplay(
+      overview.hints.totalYomitanLookupCount,
+      overview.hints.totalTokensSeen,
+    ),
     todayTokens: Math.max(
       todayRow?.words ?? 0,
       sumBy(todaySessions, (session) => session.tokensSeen),

stats/src/lib/media-session-list.test.tsx

@@ -23,6 +23,8 @@ test('MediaSessionList renders expandable session rows with delete affordance',
           lookupCount: 3,
           lookupHits: 2,
           yomitanLookupCount: 1,
+          knownWordsSeen: 6,
+          knownWordRate: 25,
         },
       ]}
       onDeleteSession={() => {}}

stats/src/lib/session-detail.test.tsx

@@ -1,7 +1,10 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 import { renderToStaticMarkup } from 'react-dom/server';
-import { SessionDetail } from '../components/sessions/SessionDetail';
+import {
+  SessionDetail,
+  getKnownPctAxisMax,
+} from '../components/sessions/SessionDetail';
 import { buildSessionChartEvents } from './session-events';
 import { EventType } from '../types/stats';
 
@@ -24,6 +27,8 @@ test('SessionDetail omits the misleading new words metric', () => {
         lookupCount: 0,
         lookupHits: 0,
         yomitanLookupCount: 0,
+        knownWordsSeen: 0,
+        knownWordRate: 0,
       }}
     />,
   );
@@ -58,3 +63,11 @@ test('buildSessionChartEvents keeps only chart-relevant events and pairs pause r
   );
   assert.deepEqual(chartEvents.pauseRegions, [{ startMs: 2_000, endMs: 4_000 }]);
 });
+
+test('getKnownPctAxisMax adds headroom above the highest known percentage', () => {
+  assert.equal(getKnownPctAxisMax([22.4, 31.2, 29.8]), 40);
+});
+
+test('getKnownPctAxisMax caps the chart top at 100%', () => {
+  assert.equal(getKnownPctAxisMax([97.1, 98.6]), 100);
+});

stats/src/lib/yomitan-lookup.test.tsx

@@ -157,6 +157,8 @@ test('SessionRow prefers token-based word count when available', () => {
         lookupCount: 0,
         lookupHits: 0,
         yomitanLookupCount: 0,
+        knownWordsSeen: 0,
+        knownWordRate: 0,
       }}
       isExpanded={false}
       detailsId="session-7"