Replace the 3D menu with a 2D | 3D switch; 3D controls in the dock; 0.6.1

The toolbar button next to Export is now a two-state switch: both
labels are visible and the filled half is the current view, so a
diagram that opens in 2D shows "2D" and one click flips it to 3D. The
dropdown is gone; nothing is greyed out and no menu stays open after a
choice.

The 3D-only controls moved to Archify's bottom-right dock beside PATH
and LENS: STACK (levels by kind, on or off), TOP (from above), and the
zoom stepper's middle button reads RESET while 3D is on, instead of a
2D zoom level that meant nothing there.

package.json

@@ -2,7 +2,7 @@
   "name": "archify-vscode-ext",
   "displayName": "Archify Diagram Viewer",
   "description": "Archify diagrams in VS Code. Write diagrams as .archify files in YAML: they open as the interactive diagram, with live updates, validation, templates and completion. Also previews Archify's own JSON files (*.architecture.json, …) and opens rendered Archify HTML.",
-  "version": "0.6.0",
+  "version": "0.6.1",
   "publisher": "root-at-skic",
   "license": "MIT",
   "icon": "media/icon.png",