Topbar rework, follow-up: Concepts says the play/pause pair sits on the middle of the window, not of the space the row has left over, and Development carries the check sum 1148

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

Concepts.md

@@ -40,8 +40,9 @@ no movement): everything that happens is defined by behavior graphs.
 
 **Toolbar and panels.** The toolbar carries five **icon buttons** and no captions (#183): the
 **menu** (three bars) on the left with *New project*, *Open project…* and *Project settings…*,
-**undo** and **redo** beside it, and **play** and **pause** in the middle — play turns into a stop
-square while a run is on, pause into a second play sign while it is held. On the right stand the
+**undo** and **redo** beside it, and **play** and **pause** in the middle — on the middle of the
+window, not of the space the row has left over — where play turns into a stop square while a run is
+on, and pause into a second play sign while it is held. On the right stand the
 notice line, the save status, the frame rate and the **Account** menu. What the bar used to spell
 out lives in the menu now: the project list in *Open project…*, the project name, the
 **start-scene switch** (*Start scene* / *Active scene*, see **Start scene**) and the collision

Development.md

@@ -13,7 +13,7 @@ npm run check        # typecheck + lint + format:check + tests, the gate CI runs
 npm run build        # writes dist/ and regenerates index.html
 ./build.sh           # the same under `set -o pipefail`, for callers that pipe the output
 php tools/make-user.php <name> <password>                     # an account; every tool signs in (see Accounts)
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1147 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1148 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