Replace the doubled-offset ID system with standard axial coordinates.
The same (q, r) pair now identifies the same hex in both flat-top and
flat-sides orientations, so shapes port correctly between layouts and
the 30° visual rotation on mode switch is expected behaviour.

- hexNeighborIds: drop flatTop param; 6 directions are layout-invariant
- generateGrid: compute axial IDs from offset loop counters
- buildHexesFromIds: use axial pixel projection formulas
- translateHexId deleted; shape moves are plain (q+dq, r+dr) addition
- originQ/originR replace originCol/originRow throughout
- saveShape stores {q, r} positions; fmtPos outputs axial coords
- migrateItem converts old {column, row} localStorage data on first load

- Redesign library items: name row, properties row, then Rename/Coords/Delete action row so name is never obscured
- Make sidebar panel collapsible and resizable by dragging the right edge
- Add folder classification: create folders, assign shapes to folders, collapse/expand folder groups
- Color-code disconnected hex clusters on the canvas; split coordinate output per cluster when saving
- Add movable coordinate origin via Ctrl+click; all coord output updates relative to the new origin, persisted across sessions
- Show group number labels on canvas hexes (centered on each cluster, only when multiple clusters present)
- Show group number labels in saved-shape thumbnails, sized to always be legible regardless of shape spread
- Stabilise cluster color assignment: clusters are numbered by painting order so adding a new cluster elsewhere does not re-color existing ones

Allow users to click and drag across hexes to add or erase selections, update pointer handling for touch
input, and add JS typings so pnpm check passes.