Fix note-field space bar hijacking video, rework Outline topics as documents

- Lesson page's global keyboard shortcuts (space/arrows for play-pause/
  seek/volume) fired regardless of focus, so typing a space in the notes
  textarea toggled the video instead of typing. Now skipped entirely
  whenever a text field/select has focus.
- Outline topics no longer spawn their own top-level collection each time.
  A topic is now a document inside one fixed, user-configured collection
  (Settings -> Outline Integration -> Default collection), and a lesson's
  note becomes a child document nested under its topic - matching how
  notes actually get organized in a real Outline instance instead of
  cluttering the collections list with one per topic.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

OfflineU-project-summary.md

@@ -248,6 +248,29 @@ before.
   session), including Settings → Test Connection hitting the real HTTP
   path.
 
+## Outline integration follow-up fixes (this session)
+
+- **Space bar bug**: the lesson page's global keyboard-shortcut handler
+  (space/arrows for play-pause/seek/volume) fired regardless of what had
+  focus, so typing a space in the notes textarea toggled the video instead.
+  Fixed with an `isTypingTarget()` guard that skips the shortcut handler
+  entirely when a textarea/input/select/contenteditable has focus.
+- **Topic model redesign**: topics used to each spawn their own top-level
+  Outline *collection*. Changed so a topic is instead a *document* inside
+  one fixed, user-configured collection (Settings → Outline Integration →
+  Default collection, e.g. "Training Notes") - a lesson's note becomes a
+  child document nested under its topic document, matching how the user
+  actually organizes their real Outline instance. `list_outline_topics()`
+  fetches the collection's documents and filters to `parentDocumentId is
+  None` locally rather than trusting `documents.list`'s `collectionId`/
+  `parentDocumentId` request filters - both are marked deprecated in
+  Outline's own API spec with unclear recursive-vs-top-level semantics, so
+  filtering the response ourselves is the version that can't be wrong.
+  Verified end-to-end against a local mock Outline server: resolving a new
+  topic creates a top-level doc, pushing a note creates a child doc under
+  it, and the child never leaks back into the topic chooser as if it were
+  a topic itself.
+
 ## Known limitations still open
 - App is unauthenticated by design (matches upstream) — settings and hidden-path
   curation apply app-wide, not per-browser/per-user.