#1018: Edit Toolbar opens a drawer beside the toolbar; tools drag in and out

The ••• button at the bottom of the toolbar no longer opens All Tools as a
centred dialog. It opens the All Tools drawer beside the toolbar, next to the
button. Escape or a click outside closes it; a click in the toolbar doesn't.
Tools that are already in the toolbar show dimmed in the drawer.

While the drawer is open the toolbar can be edited, as the public
documentation describes:
- drag a tool from the drawer onto a toolbar button's top or bottom edge
  (left or right edge in two columns) to put it in its own slot there;
- drag it onto a button's middle to add it to that button's group;
- drag a toolbar button into the drawer to take its tool out;
- drag a toolbar button to another place in the toolbar to move its tool.
A line or outline shows where the tool will go, and the dragged tool follows
the pointer. While the drawer is closed the toolbar can't be edited.

The Basic and Advanced toolbars each keep their own edits in
UiState::toolbar_edits, which is saved with the preferences. It is serde
default, so older preferences still load, and a hand-edited file is cleaned
up when it loads. An edit that brings back the default toolbar clears the
saved edits. New UI commands toolbar.addTool {tool, slot?, place?},
toolbar.removeTool {tool, group?}, toolbar.reset and
window.editToolbar {open?} let MCP and the control channel make the same
edits. The drawer also has a Reset button.

The drawer moved from dialogs/all_tools.rs into the new edit_toolbar.rs. It
is tested with headless egui frame tests driven by pointer events (placement,
Escape, click outside, dimming, drag and drop in each direction, the locked
toolbar), along with command, persistence and drop-zone tests. The three new
command labels are translated in every complete catalog, and the error
messages reuse existing translated templates.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/control-protocol.md

@@ -246,6 +246,13 @@ that open its flyout raise the strip instead. The strips (`ui.floating_flyouts`
 and the strip's top-left corner) are saved with the preferences and in user workspaces; the built-in workspaces
 float none.
 
+Edit Toolbar: the ••• button at the bottom of the toolbar (or `window.editToolbar {open?}`) opens the All Tools
+drawer beside the toolbar; Escape or a click outside closes it. While it is open, `ui.drag` a tool from it onto the
+toolbar to add it (onto a button's top or bottom edge: its own slot before or after; onto its middle: into its
+group), from the toolbar into it to remove it, or within the toolbar to move it. `toolbar.addTool {tool, slot?,
+place?}`, `toolbar.removeTool {tool, group?}` and `toolbar.reset` do the same for the current Basic or Advanced
+toolbar and return its slots; the edits (`ui.toolbar_edits`) are saved with the preferences.
+
 The Contextual Task Bar: its handle (the grip at its left end) drags it anywhere on the canvas, which always holds
 it whole, also when the window shrinks. Unpinned, the bar keeps that offset as it follows the selection, until
 another document becomes active. Its More Options (…) menu has Hide Bar (`window.taskBar`); Pin Bar Position