feat(figure): complete panel editing and image workflows

[nmrtist]

Summary

• Complete Panel editing with hierarchy selection, breadcrumbs, Layers tree, Panel composition/dissolve/merge/split, cross‑Panel moves, layout modes, alignment, locking, visibility, multi‑selection, and keyboard interaction.
• Add embedded raster‑image workflows for PNG, JPEG, TIFF, WebP, and BMP: file picker, drag‑and‑drop, clipboard import, SHA‑256 deduplication, bounded background proxies, and non‑destructive crop, rotation, opacity, and interpolation edits.
• Preserve Panel and image state through project save, reopen, Save As, autosave, recovery, undo, and redo.
• Add screen rendering for raster content while explicitly blocking export and Copy Figure paths that cannot yet include images; full export support remains scoped to the future.
• Update English and Simplified Chinese user documentation for Panels, image workflows, file formats, and troubleshooting.

Validation

• cargo pr-check
• npm run build from docs/