feat(dashboard): restyle lesson transcript and summarize actions (#758)

* feat(dashboard): restyle lesson transcript and summarize actions

Add separator lines around lesson material actions below the video,
switch transcript and summarize controls to plain ghost buttons with
hover-animated icons, and separate the two actions with a pipe when both
are visible. Display rules are unchanged.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* refactor(dashboard): inline summarize action into material actions

Fold lesson-summarize-button into lesson-material-actions and remove the
standalone component. Lessons without videos use the same actions bar with
separators disabled.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): align lesson actions with note width on mobile

Constrain material actions to max-w-2xl when there is no video so they
match the note column. Improve small-screen layout with tighter padding,
flex-wrap, and hide the pipe separator below the sm breakpoint.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* add script update

* fix(dashboard): tighten spacing between lesson video and note

Remove gap-2 from the lesson content stack and drop bottom margin on the
last video wrapper so material actions separators control the gap before
the note.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): show bottom separator on note-only lesson actions

Lessons without video were passing showSeparators=false, hiding both
lines. Split into top/bottom controls so summarize still gets a line before
the note without one above the action row.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): always show top separator on lesson material actions

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): reduce lesson material action separator margin to my-2

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* feat(dashboard): consolidate multi-video transcript actions and navigation

Register transcript sources per upload video, show a single material
actions row after all videos, and add prev/next video navigation in the
transcript side panel when multiple transcripts are available.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): address greptile review on lesson material actions

Require lessonId on material actions and stop overwriting the transcript
seek wrapper with a stale localSeekFn snapshot in the sync effect.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): stop transcript registry effect infinite loop

Replace the reactive sync effect with explicit registry updates from
loadTranscript and skip no-op transcript source writes to avoid reading
and writing transcriptSources in the same effect pass.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(ui): raise tooltip z-index above app bar side panel

Use z-menu-elevated for tooltip content so header icon tooltips are not
hidden behind the fixed transcript side panel (z-app-bar).

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

---------

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

packages/ui/src/index.css

@@ -23,8 +23,9 @@
  *   z-menu-elevated     (250) Dropdown/select/popover content that must escape a z-app-bar,
  *                             z-app-bar-elevated, or z-modal ancestor.
  *
- * Anything not listed (tooltips, dropdowns, sheets, drawers) uses Tailwind's default `z-50`,
- * which already sits above normal page content.
+ * Anything not listed (dropdowns, sheets, drawers) uses Tailwind's default `z-50`,
+ * which already sits above normal page content. Tooltips use `z-menu-elevated` so they
+ * remain visible over `z-app-bar` chrome such as the transcript side panel.
  */
 @utility z-app-bar {
   z-index: 100;