feat(locker): create cursor packs from your own images

[Slush97]

Adds a Create button to the Locker's Cursor tab that builds a cursor pack from your own images.

Dialog. One tile per stock cursor (Pointer 48x58, Ping 48x58, Shop 60x60, Commend 88x88). Picking an image opens CardCropper in a new cursor mode: the image starts whole and flush top-left, it can zoom out past cover (whatever it doesn't cover stays transparent), and a crosshair marks the click point. Slots left empty keep the game's own cursor. "Create and apply" installs and applies the pack. "Export" writes the same files to a zip that imports back as the same pack.

Hotspot detection (src/lib/cursorHotspot.ts). Guesses the click point from the alpha mask: the sharpest convex-hull corner, biased toward top-left like the stock pointers. Reticles (quarter-turn symmetric) and blunt art aim at the middle. Fully opaque art gets the stock 0, 0. A click in the cropper moves it.

Writing the pack. The renderer encodes 32-bit BI_RGB BMPs with alpha in the fourth byte, the same layout as the stock files (src/lib/cursorBmp.ts). Main validates names and signatures as with imports, then writes a cursor.res that starts from the stock copy and overrides only the cursors you replaced, so the commend cursor keeps its 22, 2 hotspot. Entries are keyed by file stem (cursor, cursor_ping), matching the community packs on GameBanana. installGroups is split so archive imports and created packs share installSets.

New IPC: cursors:create, cursors:export.

Checks: tsc -b, eslint, ui:check, vitest (180 files, 2662 tests), i18n check + manifest, electron-vite build with 0 unresolved imports. Not yet checked in-game.