fix: half-open mark ranges + robust active-card scroll

- Playhead-in-bar tests (active annotation(s), drawing/note bindings) are now
  half-open [lo hi) via a shared in-bars? helper. merge-bars ceils the exclusive
  end up to the next clip's first frame, so the old inclusive <= double-counted
  the boundary: two annotations lit at once and clip A's drawing bled onto clip
  B's first frame.
- commentary-scroll uses scrollIntoView instead of manual offsetTop math, which
  broke once cards can nest (a nested card's offsetParent is its parent .ann).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tl/src/tl/subs.cljs

@@ -146,13 +146,18 @@
         (sort-by str/lower-case)
         vec)))
 
+;; playhead inside a bar — HALF-OPEN [lo hi), so the boundary frame belongs to the
+;; next bar only (no double-highlight, no drawing bleeding onto the next clip).
+(defn- in-bars? [bars ph]
+  (some (fn [[lo hi]] (and (<= lo ph) (< ph hi))) bars))
+
 ;; the annotation the playhead is currently inside (or the latest one passed) —
 ;; drives the rolling highlight/scroll in the commentary
 (rf/reg-sub
  ::active-annotation
  :<- [::annotations] :<- [::playhead]
  (fn [[anns ph] _]
-   (:id (or (some (fn [a] (when (some (fn [[lo hi]] (<= lo ph hi)) (:bars a)) a)) anns)
+   (:id (or (some (fn [a] (when (in-bars? (:bars a) ph) a)) anns)
             (last (filter #(<= (:start %) ph) anns))
             (first anns)))))
 
@@ -162,7 +167,7 @@
  ::active-annotations
  :<- [::annotations] :<- [::playhead]
  (fn [[anns ph] _]
-   (into #{} (keep (fn [a] (when (some (fn [[lo hi]] (<= lo ph hi)) (:bars a))
+   (into #{} (keep (fn [a] (when (in-bars? (:bars a) ph)
                              (:id a)))
                    anns))))
 
@@ -223,7 +228,7 @@
 (defn- gids-at [entries ph]
   (persistent!
    (reduce (fn [acc {:keys [gids bars]}]
-             (if (some (fn [[lo hi]] (<= lo ph hi)) bars) (reduce conj! acc gids) acc))
+             (if (in-bars? bars ph) (reduce conj! acc gids) acc))
            (transient #{}) entries)))
 
 ;; drawings to render over the video now (playhead in a bound mark's span).

tl/src/tl/views.cljs

@@ -1099,7 +1099,10 @@
     (r/after-render
      (fn [] (when-let [c @el]
               (when-let [node (and active (.querySelector c (str "#ann-" (name active))))]
-                (set! (.-scrollTop c) (max 0 (- (.-offsetTop node) (/ (.-clientHeight c) 3))))))))
+                ;; scrollIntoView (not manual offsetTop math): a nested card's
+                ;; offsetParent is its parent .ann (position:relative), so offsetTop
+                ;; would be measured inside the parent, not the scroll container.
+                (.scrollIntoView node #js {:block "center" :behavior "smooth"})))))
     nil))
 
 (defn commentary []