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/web/static/js/search.js

@@ -59,7 +59,7 @@
     const html = items.map((r, i) => {
       const thumb = r.thumb_url
         ? `<div class="hidden sm:block w-20 h-20 shrink-0 overflow-hidden rounded-2xl bg-[color:var(--ink)]/5">
-             <img src="${escapeHTML(r.thumb_url)}" alt="" loading="lazy" decoding="async"
+             <img src="${escapeHTML(r.thumb_url)}" alt="${escapeHTML(r.headline || "")}" loading="lazy" decoding="async"
                   class="h-full w-full object-cover">
            </div>`
         : `<div class="hidden sm:flex w-20 h-20 shrink-0 items-center justify-center rounded-2xl bg-[color:var(--ink)]/5 text-2xl">${escapeHTML(r.channel_emoji || "·")}</div>`;