Compositions: band selection and copying clips (#417)

- Compositions: dragging a band selects items, with Alt clips.
  Clips copy and paste like items and move on until they fit.
  "Copying clips" is gone from Not yet.
- Development: 2057 editor checks.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Compositions.md

@@ -91,6 +91,9 @@ the clips as narrower bars above them. The header bar has **+ Track**, **Play**
   video, one line per round. An overlap is darkened, and a line marks the end of the item below.
 - **Click** picks an item or a clip, `Ctrl`-click adds or removes one. A click on a track head picks
   the track, a click in the ruler moves the playhead there, and dragging in it scrubs.
+- **A band** dragged from an empty spot picks the items it touches. With `Alt` held it picks the
+  clips instead and may start anywhere, on an item too. With `Ctrl` it adds to what is picked. A
+  pick holds items or clips, never both.
 - **The right-click menu** on an item: *Fit to media*, *Make project asset* (only for an item
   wearing a sprite of the composition's own), *Remove item*. On a clip: *Open animation*,
   *Remove clip*. On a track head or an empty stretch of a track, as in the Song tab: *Add track
@@ -101,7 +104,9 @@ the clips as narrower bars above them. The header bar has **+ Track**, **Play**
   playhead, on the picked track, else on the top track of the picked items. Several items keep
   their distances and their tracks to each other. The same copy pastes into a scene as plain
   objects; objects copied from a scene do not paste into a composition, they have no timing.
-  Clips cannot be copied yet.
+  **Picked clips** are copied and pasted the same way, into this composition or another. As clips
+  of a track never overlap, a paste that would lie over a clip moves on, all its clips together,
+  to the first frame where they fit.
 - `Delete` removes the picked items with their objects, the picked clips or the picked track.
 - **Play** plays from the playhead at the composition's frame rate, round with its Loop; from the
   end it starts at 0. The wheel zooms the time, the middle button or `Shift`-drag pans. Both glide
@@ -163,4 +168,4 @@ with the same row binding the `AnimationSystem` uses.
 
 - Sounds and songs as items on a track (#418).
 - Dragging a clip of a video straight out of the Video tab onto a track.
-- Copying clips, a composition inside a composition, and *Sort with parent* for a placement.
+- A composition inside a composition, and *Sort with parent* for a placement.

Development.md

@@ -21,7 +21,7 @@ php tests/php/releases.test.php                               # the release stor
 php tests/php/files.test.php                                  # uploaded files in a folder per account (#344), the same way
 php tests/php/videos.test.php                                 # the video store, its queue and the worker (#402), with the
                                                               #   real ffmpeg: the CI image and game-maker-video have it
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 2056 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 2057 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result