refactor: simplify image location loading

[lawvs]

Summary

• Add independent image location reader using exifr and raw GPS tag fallback.
• Add selection location loader so Eagle selection state no longer owns file reading or EXIF parsing.
• Make useEagleSelection race-safe with abort/generation guards while preserving the existing UI-facing return shape.
• Remove legacy piexif-ts/exif-reader/buffer parser path and dependencies.

Verification

• pnpm test
• pnpm run type-check
• pnpm run lint:check
• pnpm run build

Note: build still emits the existing Vite chunk-size warning for maplibre-gl.