Add per-story views, trending, and reader reading-experience upgrades

Surface read counts and sharpen the reader:
- story_views table + RecordStoryView on /api/article (background,
  filter-guarded); "Popular this week" home rail via TrendingStories;
  read-count badge and reading-time chip decorated onto every listing
- reader: signed-in-only read-aloud (TTS), native share/copy, and an
  Aa typography popover (size/serif/sepia) persisted per device
- real alt text on card/reader/related/search images; time-of-day Pete
  greeting on the home hero
- harden exec() to skip (not panic) on a nil DB so background writes
  can't crash on a closed handle

Tests: story_views_test.go, trending_test.go. Suite green, CSS rebuilt.

internal/storage/metrics.go

@@ -10,6 +10,10 @@ const secondsPerDay = 86400
 // unixDay returns the current UTC day number (floor(unix / 86400)).
 func unixDay() int64 { return nowUnix() / secondsPerDay }
 
+// UnixDay is the exported current UTC day number, for callers building
+// day-windowed queries (e.g. the trending rail's 7-day cutoff).
+func UnixDay() int64 { return unixDay() }
+
 // RecordPageView increments the all-time and per-day view counter for a coarse
 // path label ("home", a channel slug, …). Fire-and-forget: a failure here must
 // never affect serving a page, so errors are logged and swallowed.
@@ -28,6 +32,61 @@ func RecordVisitor(token string) {
 		unixDay(), token)
 }
 
+// RecordStoryView bumps the per-day read counter for a single story. Called
+// when a visitor opens the story in reader mode. Fire-and-forget like the other
+// metrics writes: a failure here must never affect serving the article.
+func RecordStoryView(id int64) {
+	exec("record story view",
+		`INSERT INTO story_views (story_id, day, views) VALUES (?, ?, 1)
+		 ON CONFLICT(story_id, day) DO UPDATE SET views = views + 1`,
+		id, unixDay())
+}
+
+// StoryViewTotals returns all-time read counts for the given story ids, as a
+// map keyed by id. Ids with no recorded views are simply absent from the map
+// (callers treat missing as zero). Best-effort: on error it returns whatever it
+// managed to read, so a metrics hiccup never blanks a page.
+func StoryViewTotals(ids []int64) map[int64]int {
+	out := make(map[int64]int, len(ids))
+	if len(ids) == 0 {
+		return out
+	}
+	ph, args := intInClause(ids)
+	rows, err := Get().Query(
+		`SELECT story_id, SUM(views) FROM story_views
+		 WHERE story_id IN (`+ph+`) GROUP BY story_id`, args...)
+	if err != nil {
+		slog.Error("metrics: story view totals query failed", "err", err)
+		return out
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var id int64
+		var n int
+		if err := rows.Scan(&id, &n); err != nil {
+			slog.Error("metrics: scan story view total failed", "err", err)
+			continue
+		}
+		out[id] = n
+	}
+	return out
+}
+
+// intInClause builds a "?, ?, …" placeholder string and matching args slice for
+// a SQL IN (…) over int64 ids.
+func intInClause(ids []int64) (string, []any) {
+	ph := make([]byte, 0, len(ids)*2)
+	args := make([]any, len(ids))
+	for i, id := range ids {
+		if i > 0 {
+			ph = append(ph, ',')
+		}
+		ph = append(ph, '?')
+		args[i] = id
+	}
+	return string(ph), args
+}
+
 // PathStat is one row of the per-page usage breakdown.
 type PathStat struct {
 	Path  string