Fix #495: panels, panel groups and the Tools panel undock into floating panels

Nothing could be undocked: the dock's tabs only switched panels, the icon
column only popped its panels out next to it, and only tool flyouts
(#437) could float.

- A dock tab, a panel icon or a popped-out panel's title dragged out of
  the dock floats that panel inside the app window; the strip right of
  the dock's tabs floats the whole Properties | Layers | Libraries group.
- A floating group moves by its title bar (or the strip right of its
  tabs); a tab dragged out of it floats on its own; dropped on another
  group's title bar or tabs it stacks with that group; dropped on the
  dock, which lights up under the pointer, its panels go back where they
  live in the dock (tabbed group or icon column). Its x does the same.
- The Tools panel floats by its title bar or grip and docks again on the
  window's left edge, which lights up the same way.
- window.panel.float {panel, x?, y?, onto?, group?} and window.panel.dock
  {panel, group?} (panel "tools" for the Tools panel) for the control
  channel and MCP; every panel menu ends with Float Panel / Dock Panel;
  window.panel on a floating panel shows its tab.
- Floating groups and the Tools panel's position are kept with the
  preferences and in user workspaces (built-ins dock everything),
  sanitized on load, and clamped into a smaller window when drawn.
- One move state in egui temp memory drives every drag, so a tab torn off
  keeps following the pointer; per frame the work is a lookup per panel.
- Icon buttons can be drawn for a caller's response (paint_icon_button),
  so the column's icons keep their ids when one above them floats.
- Translations (ja, es, zh-hans, zh-hant; cs and pt-br for the commands),
  es @msg rows, docs/control-protocol.md and ROADMAP.

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

docs/control-protocol.md

@@ -214,6 +214,20 @@ Bar Position (`window.taskBar.reset`), which unpins it and puts it back under th
 Panel. As in Illustrator, neither the position nor the pin is saved: each launch starts with the bar under the
 selection.
 
+Floating panels: dragging a dock tab, a panel icon or a popped-out panel's title out of the dock floats that panel
+inside the window, and the strip right of the dock's tabs floats the whole Properties | Layers | Libraries group. A
+floating group moves by its title bar (or the strip right of its tabs); a tab dragged out of it floats on its own;
+dropped on another group's title bar or tabs it stacks with that group, and dropped on the dock (lit up while the
+pointer is over it) or closed with its × its panels go back to the tabbed group or the icon column.
+`window.panel.float {panel, x?, y?, onto?, group?}` floats a panel (with `group`, its whole group) with its top-left
+corner at `x`, `y` (window points; default cascaded), or stacks it with the floating group holding `onto`;
+`window.panel.dock {panel, group?}` puts it back. `panel` takes the `window.panel` ids and labels, and `"tools"` for
+the Tools panel, which floats by its title bar and docks on the window's left edge. `window.panel` on a floating
+panel shows its tab. `ui.floating_panels` in `ui.inspect` lists the groups (panel ids, the index of the tab shown,
+the top-left corner) and `ui.toolbar_pos` the Tools panel's corner (null: docked); both are saved with the
+preferences and in user workspaces (the built-in workspaces dock everything), and a corner saved on a bigger window
+is clamped into this one when drawn. Floating panels stay inside the app window (no separate OS windows).
+
 Flatten Transparency: `ui.flattenTransparencyDialog` opens the `flattenTransparency` dialog for the selection
 (fields `preset`: a preset name, setting it loads that preset's options; the option keys of
 `object.flattenTransparency`: `balance` 0–100, `lineArtPpi` and `gradientPpi` 1–2400, `textToOutlines`,