Part of #1429: Edit and Object commands on many objects take time linear in the document

Delete, Cut, Group, Make Compound Path, Make Clipping Mask, Send to
Current Layer, Ungroup and Release Compound Path removed, inserted or
moved one object at a time. duplicate_in inserted one copy at a time;
Duplicate, Copy in the Move, Rotate, Scale, Reflect and Shear dialogs,
Transform Again after a copy, Transform Each with Copy, the perspective
copies and each move of an Alt-drag call it. Each insertion or removal
moved the later objects of the same layer or group to other indices.
The next lookup by id then walked the tree, and after every fourth such
walk Document::index_path rebuilt the whole lookup cache. Each command
did work that grew with the number of objects times the size of the
document: with 25,000 rectangles selected, a release build of
vectorcraft-cli took 7.2 s to group them and 11.5 s to copy them with
object.transform.

Document::remove_many, Document::wrap and Document::insert_beside
remove nodes, wrap them in a new node, or put nodes directly above or
in place of their anchors, in one pass over the children of each
parent. Each finds the nodes with one index_paths call, checks every id
before it changes anything, and clears the lookup cache once. The
commands above use them. The objects keep their order, the copies take
their ids in the same order, and the selection, the undo step and the
journal are the same. duplicate_in still copies one root at a time when
a root is listed twice or lies inside another root. A release build
with this change groups the 25,000 rectangles in 27 ms and copies them
in 121 ms.

Docs: docs/target-app-parity.md.

docs/target-app-parity.md

@@ -506,6 +506,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
   cursors. DPI/hotspot and preference checks in `cursors.rs` and `tests_prefs.rs` cover #1269;
   actual OS display and Caps Lock remain unverified. Behaviour reference: [public tool-pointer documentation](https://helpx.adobe.com/illustrator/using/tools.html#change_tool_pointers).
 - **Performance:** 20k shapes + 1k texts render in 27 ms per full-retina frame (7.8 ms zoomed), 7× faster than the first version. The UI thread never blocks. The web build is 7.1 MB gzipped.
+  Delete, Cut, Group, Ungroup, Make and Release Compound Path, Make Clipping Mask, Send to Current Layer, Duplicate, Copy in the Move, Rotate, Scale, Reflect and Shear dialogs, Transform Each with Copy and each move of an Alt-drag take time in proportion to the size of the document (#1429).
 - **Graphics processor:** the canvas is rasterized on the CPU and the GPU only composites it, so any GPU that can show the window will do. Preferences › Performance › Graphics Processor (`gpuPreference`) is Automatic by default: the power-saving GPU on Windows and macOS (the integrated one on hybrid-graphics laptops, where presenting from the discrete GPU made the window flicker, #306), and the GPU the desktop runs on under Linux, where KWin on an NVIDIA GPU refused frames from a Ryzen's integrated GPU and 0.5.0 crashed at startup (#502). Power Saving and High Performance pick a kind of GPU; `WGPU_POWER_PREF`, `WGPU_ADAPTER_NAME` and `WGPU_BACKEND` override them. The app picks among the adapters that can present to the window (native backends before OpenGL, hardware before software, and on Windows a GPU's DX12 adapter before its Vulkan one: Intel's Vulkan driver made the whole window flicker black, #545), and if the window fails on one while starting up it starts again without it instead of crashing; Help › About, `ui.inspect` and the log name the adapter in use. When the browser drops the page's WebGPU device or WebGL context, the web build writes recovery copies, starts again on new graphics with the same app and uploads its textures again; if it can't, it removes the stale canvas and says to reload, which offers the copies back. The desktop app writes the copies and says to restart (#369). On Windows and Linux the tools' cursors are OS cursors (bitmaps rasterized once per display scale), which the system moves itself: painted into the window, they trailed the pointer by the frames waiting to be shown, and the window now queues one frame instead of two (#444). macOS and the web still paint them (macOS sizes cursor bitmaps in points, eframe has no bitmap cursors on the web). Pens and touch drive the tools as the mouse does, and a tap pressed and lifted within one frame clicks where it tapped (#491); pen pressure reaches the Liquify tools' Use Pressure Pen on Windows, while winit 0.30 reports none on macOS or Linux and egui none on the web. On Linux, see `docs/development.md` for pens under Wayland.
 - **Tests and robustness:** ~2,840 automated tests: model-based property tests, a junk-parameter sweep over every command, import fuzzing (SVG, PDF, libraries), golden renders, and MCP end-to-end tests over stdio. Shipped code never panics (workspace lints and a rollback safety net; see `docs/development.md`).
 - **Raster-effect resolution in PDF:** when the 64 million pixel cap on an effect image renders an object's raster effects below the document's raster effects resolution, PDF export warns once per object with the requested and the lowest achieved ppi (`crates/engine/src/tests_pdfraster.rs`).