Re-record the manual on the keyboard layout, and stop the zoom caption promising blocks

Every scene was recorded again on a build of this branch rebased onto the
keyboard work and TD-1, since nearly every scene depends on files those
changed: the develop top bar now carries a star strip and Pick/Reject, the
roll shows flags and stars, and the grid's selection bar gains Label and
Flag. `--changed` could not be trusted to find them, because the rebase
made each picture's commit newer than the sources it was recorded from.

The develop-zoom caption said the wheel goes on "until the pixels are
blocks". On Xvfb the deepest frames come out smooth even though the app
draws past 1:1 nearest-neighbour on a real display (confirmed by eye on
the desktop), and a GIF shrunk to 960 wide could not show 3-pixel blocks
anyway. The caption now says what the clip shows; the prose above it,
which describes what the app does, stays.

docs/manual/README.md

@@ -129,7 +129,7 @@ wheel zooms to any amount in between. Past 1:1 the file's own pixels are
 drawn as hard-edged blocks rather than smoothed, so what you see is what
 the sensor recorded.
 
-![Zooming to 1:1, panning, then on in with the wheel until the pixels are blocks](media/develop-zoom.gif)
+![Zooming to 1:1 with a double-click, panning, then further in with the wheel](media/develop-zoom.gif)
 
 ### Moving between photographs
 

docs/manual/index.html

@@ -221,7 +221,7 @@ Hold <code>Before</code> to see the photograph as it was.</p>
 wheel zooms to any amount in between. Past 1:1 the file's own pixels are
 drawn as hard-edged blocks rather than smoothed, so what you see is what
 the sensor recorded.</p>
-<figure><img loading="lazy" src="media/develop-zoom.gif" alt="Zooming to 1:1, panning, then on in with the wheel until the pixels are blocks"><figcaption>Zooming to 1:1, panning, then on in with the wheel until the pixels are blocks</figcaption></figure>
+<figure><img loading="lazy" src="media/develop-zoom.gif" alt="Zooming to 1:1 with a double-click, panning, then further in with the wheel"><figcaption>Zooming to 1:1 with a double-click, panning, then further in with the wheel</figcaption></figure>
 <h3 id="moving-between-photographs">Moving between photographs</h3>
 <p>The roll along the foot of the canvas holds the photographs the grid was
 showing; click one to open it. The right arrow, <code>D</code> or space opens the next,

tools/manual/scenes.py

@@ -768,8 +768,10 @@ def develop_light():
 
 @scene(media=['develop-zoom.gif'], sources=DEVELOP_SRC + ['ui/dr-ui/src/develop/render.rs'])
 def develop_zoom():
-    """1:1 with a double-click, a pan, and then on in with the wheel until
-    the file's own pixels are hard-edged blocks — which is where it ends."""
+    """1:1 with a double-click, a pan, and then further in with the wheel.
+    Recorded on Xvfb, the deepest frames come out smooth although the app
+    draws past 1:1 with nearest-neighbour on a real display; until that is
+    understood, this scene does not claim to show the blocks."""
     at_develop()
     a = dr.photo(0.62, 0.52)         # the fire escape and the air conditioner
     rec('develop-zoom')