Add Favorites, storage drill-down, keyboard shortcuts, and What's New

- Favorites: star toggle on course rows, the course page, and a new
  dashboard card; rebased on rename/move, backed up/restored, and
  caught by stale-reference cleanup (also fixed a pre-existing gap
  where favorites.json wasn't in the backup file list).
- Storage Usage: click a folder row to drill into its contents one
  level at a time, with a Back button.
- Lesson player: added ,/. (speed step), [/] (prev/next lesson), and
  F (fullscreen) keyboard shortcuts.
- Settings: a CHANGELOG.md-backed "What's New" list, since VERSION
  alone only ever shows the current build.

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

README.md

@@ -53,7 +53,10 @@ guessing. Deliberately not derived from `git rev-parse` at Docker build
 time - Dockhand's build context doesn't reliably have `.git` available,
 which silently produced "unknown" instead of an actual commit. Reads as
 `dev` outside Docker (no `VERSION` file to read, e.g. before the first
-commit that adds one).
+commit that adds one). `CHANGELOG.md` at the repo root accumulates that
+same line on every commit (newest first) instead of overwriting it, and
+shows as a "What's New" list under the version line in Settings - so you
+can see recent history, not just the current build.
 
 ---
 
@@ -186,18 +189,22 @@ silently stay blank instead of erroring.
   listed (and reversible) under "Ignored matches," and persist through
   backup/restore alongside hidden paths and Next Up.
   - *Clean Up Stale References*: finds entries in the hidden-paths list,
-  Next Up queue, or Recently Viewed history that point at a path no longer
-  on disk - normally from renaming/moving/deleting a course directly on
-  the NAS instead of through the app (doing it through the app already
-  keeps these in sync). Review individually or clear them all at once;
-  course files themselves are never touched.
+  Next Up queue, Favorites, or Recently Viewed history that point at a path
+  no longer on disk - normally from renaming/moving/deleting a course
+  directly on the NAS instead of through the app (doing it through the app
+  already keeps these in sync). Review individually or clear them all at
+  once; course files themselves are never touched.
   - *Storage Usage*: disk usage per top-level library folder, largest
   first, with a simple proportional bar per entry - manually triggered
-  (it reads every file's size) rather than run automatically.
+  (it reads every file's size) rather than run automatically. Click any
+  folder row to drill into its own contents one level at a time, with a
+  Back button to climb back out.
 
 **Dashboard**
 - Library-wide stats (courses, lessons completed, time watched, time
   remaining, day streak) and a 90-day activity heatmap
+- Favorites — star any course from its list row or its own page for quick
+  access from the dashboard, independent of recency or curated queues
 - Next Up queue (manually curated, reorderable)
 - Pick Back Up (courses with progress that have gone stale)
 - Recently Added / Recently Viewed
@@ -207,6 +214,10 @@ silently stay blank instead of erroring.
 **Playback & progress**
 - Video/audio player with resize, playback-speed presets, and resume-from-
   last-position
+- Keyboard shortcuts on the lesson page: Space (play/pause), ←/→ (seek
+  10s), ↑/↓ (volume), `,`/`.` (step playback speed), `[`/`]` (previous/next
+  lesson), `F` (fullscreen), `N` (quick-capture a note) - see Help for the
+  full list
 - Auto-tracks watch progress and completion per lesson
 - Video/audio durations read via `ffprobe` and cached persistently per
   course (`.offlineu_duration_cache.json`), so total runtime and per-lesson
@@ -236,9 +247,9 @@ silently stay blank instead of erroring.
 
 **Backup & integrations**
 - One-click backup export and restore: settings, hidden-path choices, the
-  Next Up queue, recent-view history, ignored-duplicate pairs, Outline
-  config, and every course's progress/notes as a zip (not the course files
-  themselves). Restore
+  Next Up queue, Favorites, recent-view history, ignored-duplicate pairs,
+  Outline config, and every course's progress/notes as a zip (not the
+  course files themselves). Restore
   overwrites current data and needs a matching course folder to already
   exist for each course's progress to land - it's a "put my data back"
   action, not a merge
@@ -256,6 +267,7 @@ Everything under `OFFLINEU_DATA_DIR` (app-wide, not tied to a course):
 | `settings.json`        | Theme, layout, library path, etc.          |
 | `hidden_paths.json`    | Courses/folders curated out of the browser |
 | `next_up.json`         | The Next Up queue, in order                |
+| `favorites.json`       | Favorited course paths                     |
 | `recent_views.json`    | Cross-course "Recently Viewed" history     |
 | `ignored_duplicates.json` | Course-path pairs confirmed not duplicates |
 | `outline_config.json`  | Outline API token/collection mapping       |