feat(stats): reading statistics — session capture wired + /stats page + widget + per-book card

The design parked in the handoff (multi-tier stats off reading_history;
bookorbit-style in data, not looks) is in. The real prerequisite work
was data: reading_history existed but NOTHING wrote to it — the whole
stats feature was sitting on an empty table.

- CAPTURE (no client changes, no repo-boundary crossings): every
  successful progress write through SaveProgress (KOReader + app + web
  + Kobo + offline queue — the one chokepoint) now records one
  reading_history session row: span = the interval since the PREVIOUS
  write instant, pages = positive page delta when both sides know the
  page index, marker rows for first contact. Spans over 2h are kept as
  zero-second markers (overnight suspend→resume, offline flushes must
  not inflate totals) — the honest 'sync cadence, not a stopwatch'
  caveat stays. device_id only when a REAL device row matches (the
  web/app progress path historically stuffs the USER id into DeviceID
  — probe instead of trusting it; FK violation would silently drop
  every capture). Source preserved in device_metadata.

- API: /api/stats/summary?range=7|30|90|year (totals, zero-filled
  daily arrays, streaks, most-active day/weekday, top books, library
  breakdown — one call), /api/stats/this-week (widget: rolling 7d vs
  previous + streak), /api/stats/books/:id (lifetime + recent
  sessions). All bucketed in the user's timezone; finished ≡ any push
  ≥0.995; visible-library lens enforced at source. Legacy
  /api/analytics/* kept untouched. Range windows anchor end-of-day to
  the START of today (blasting the clock time into tomorrow resolved
  'today' a calendar day late — found by the streak test).

- /stats page (sidebar Stats between Progress and Devices, previously
  /analytics was an orphan): range selector, five stat cards, two
  Chart.js v4 charts (daily minutes bar, pages/day line — chunked via
  dynamic import so main.js stays untouched), per-library breakdown,
  most-read list, empty-state explainer. /analytics now 301s to /stats.
  The orphaned analytics.templ + analytics.ts removed (their containers
  and the page JSON never matched; the page was astub).

- Dashboard 'This Week' widget (server-rendered, suppressed on service
  failure) and the book detail 'Your Reading Stats' card (lifetime
  totals of the viewer's own sessions) complete the tiers: per-user
  default, per-library breakdown inline, per-book on the page,
  per-system/admin aggregate parked as before.

Tests: statistics_test.go (capture semantics at the chokepoint,
tz/day buckets, zero-fill, streak math, finished detection, range
validation, auth gate, widget, per-book lifetime). Full suite PASS.

internal/router/frontend.go

@@ -473,8 +473,30 @@ func registerFrontendRoutes(cfg *Config) {
 		sectionData := handlers.MarkActiveConflictsSections(c.Request().Context(), cfg.Queries, userPgID, handlers.BuildSections(visibleSections, libraryID))
 		allSectionsData := handlers.BuildSections(allSections, libraryID)
 
+		// “This week” widget: the user's rolling 7-day reading pulse, from
+		// the same session seed the /stats page uses. Suppressed when the
+		// service fails (dashboard always renders).
+		var week *templates.WeekStatsData
+		if cfg.StatisticsService != nil {
+			weekSvc, weekErr := cfg.StatisticsService.ThisWeek(c.Request().Context(),
+				pgtype.UUID{Bytes: userUUID, Valid: true}, user.Timezone)
+			if weekErr == nil {
+				week = &templates.WeekStatsData{
+					WeekMinutes:   weekSvc.WeekMinutes,
+					WeekPages:     weekSvc.WeekPages,
+					WeekSessions:  weekSvc.WeekSessions,
+					WeekBooks:     weekSvc.WeekBooks,
+					PrevMinutes:   weekSvc.PrevMinutes,
+					ActiveToday:   weekSvc.ActiveToday,
+					CurrentStreak: weekSvc.CurrentStreak,
+				}
+			} else {
+				log.Printf("ThisWeek widget failed: %v", weekErr)
+			}
+		}
+
 		var buf bytes.Buffer
-		err = templates.Dashboard(user, sectionData, allSectionsData, libRes.Libraries, libraryID, prefs.HiddenCollections, limit, errorMsg).Render(c.Request().Context(), &buf)
+		err = templates.Dashboard(user, sectionData, allSectionsData, libRes.Libraries, libraryID, prefs.HiddenCollections, limit, week, errorMsg).Render(c.Request().Context(), &buf)
 		if err != nil {
 			return err
 		}
@@ -948,14 +970,22 @@ func registerFrontendRoutes(cfg *Config) {
 		return c.HTML(http.StatusOK, buf.String())
 	})
 
-	// Analytics page
+	// Analytics page → /stats (the rebuilt reading-statistics page;
+	// nobody bookmarks orphan pages twice).
 	frontendProtected.GET("/analytics", func(c *echo.Context) error {
+		return c.Redirect(http.StatusMovedPermanently, "/stats")
+	})
+
+	// Reading statistics page — per-user by default, with library
+	// breakdown; the per-book tier lives on the book detail page and the
+	// dashboard carries the "this week" widget.
+	frontendProtected.GET("/stats", func(c *echo.Context) error {
 		user, err := getTemplateUserWithTheme(c, cfg)
 		if err != nil {
 			return renderErrorPage(c, "Error loading user", "user_load_error")
 		}
 		var buf bytes.Buffer
-		err = templates.Analytics(user).Render(c.Request().Context(), &buf)
+		err = templates.Stats(user).Render(c.Request().Context(), &buf)
 		if err != nil {
 			return err
 		}
@@ -1577,6 +1607,24 @@ func registerFrontendRoutes(cfg *Config) {
 			UserID:      pgUserID,
 		})
 
+		// Per-book reading stats (the viewer's own history card) — nil
+		// keeps the card off the page for untouched books / other users.
+		var bookStats *handlers.BookStatsData
+		if cfg.StatisticsService != nil {
+			if svcStats, serr := cfg.StatisticsService.BookStats(c.Request().Context(),
+				pgUserID, mediaUUID, user.Timezone); serr == nil && svcStats.SessionCount > 0 {
+				bookStats = &handlers.BookStatsData{
+					TotalMinutes: svcStats.TotalMinutes,
+					TotalPages:   svcStats.TotalPages,
+					SessionCount: svcStats.SessionCount,
+					MaxProgress:  svcStats.MaxProgress,
+					Finished:     svcStats.Finished,
+					FirstSession: svcStats.FirstSession,
+					LastSession:  svcStats.LastSession,
+				}
+			}
+		}
+
 		// Assemble response (no field duplication!)
 		detail := handlers.MediaDetail{
 			MediaItems:         mediaItem, // Embedded - ALL fields available
@@ -1584,6 +1632,7 @@ func registerFrontendRoutes(cfg *Config) {
 			Rating:             rating,
 			Collections:        collections,
 			ReadingProgress:    progress,
+			BookStats:          bookStats,
 			ActiveConflict:     activeConflict,
 			NotesCount:         len(notes),
 			HighlightsCount:    len(highlights),