feat(stats): add stats server, API endpoints, config, and Anki integration

- Hono HTTP server with 20+ REST endpoints for stats data
- Stats overlay BrowserWindow with toggle keybinding
- IPC channel definitions and preload bridge
- Stats config section (toggleKey, serverPort, autoStartServer, autoOpenBrowser)
- Config resolver for stats section
- AnkiConnect proxy endpoints (guiBrowse, notesInfo)
- Note ID passthrough in card mining callback chain
- Stats CLI command with autoOpenBrowser respect

src/shared/ipc/contracts.ts

@@ -28,6 +28,7 @@ export const IPC_CHANNELS = {
     kikuFieldGroupingRespond: 'kiku:field-grouping-respond',
     reportOverlayContentBounds: 'overlay-content-bounds:report',
     overlayModalOpened: 'overlay:modal-opened',
+    toggleStatsOverlay: 'stats:toggle-overlay',
   },
   request: {
     getVisibleOverlayVisibility: 'get-visible-overlay-visibility',
@@ -40,6 +41,7 @@ export const IPC_CHANNELS = {
     getMecabStatus: 'get-mecab-status',
     getKeybindings: 'get-keybindings',
     getConfigShortcuts: 'get-config-shortcuts',
+    getStatsToggleKey: 'get-stats-toggle-key',
     getControllerConfig: 'get-controller-config',
     getSecondarySubMode: 'get-secondary-sub-mode',
     getCurrentSecondarySub: 'get-current-secondary-sub',
@@ -60,6 +62,19 @@ export const IPC_CHANNELS = {
     jimakuListFiles: 'jimaku:list-files',
     jimakuDownloadFile: 'jimaku:download-file',
     kikuBuildMergePreview: 'kiku:build-merge-preview',
+    statsGetOverview: 'stats:get-overview',
+    statsGetDailyRollups: 'stats:get-daily-rollups',
+    statsGetMonthlyRollups: 'stats:get-monthly-rollups',
+    statsGetSessions: 'stats:get-sessions',
+    statsGetSessionTimeline: 'stats:get-session-timeline',
+    statsGetSessionEvents: 'stats:get-session-events',
+    statsGetVocabulary: 'stats:get-vocabulary',
+    statsGetKanji: 'stats:get-kanji',
+    statsGetMediaLibrary: 'stats:get-media-library',
+    statsGetMediaDetail: 'stats:get-media-detail',
+    statsGetMediaSessions: 'stats:get-media-sessions',
+    statsGetMediaDailyRollups: 'stats:get-media-daily-rollups',
+    statsGetMediaCover: 'stats:get-media-cover',
   },
   event: {
     subtitleSet: 'subtitle:set',