Cobblemon Info for REI / JEI / EMI

Added

• Added a generated Pokemon sprite atlas system for REI, JEI, and EMI so Pokemon browser entries render shipped/generated 2D sprites before falling back to Cobblemon's model-backed fake items
• Added stable sprite keys based on render species plus sorted normalized aspects, so regional and alternate-form sprites can be cached independently from base species sprites
• Added /cobbledex sprites build to snapshot the current pack's surfaced Pokemon and forms into cobbledex-sprites/pokemon_atlas.png, pokemon_atlas.json, and individual sprites/*.png files
• Added /cobbledex sprites reload to reload the generated atlas without restarting the client

Improved

• Kept existing fake-item/model rendering as the final fallback when no generated 2D sprite exists, preserving rare/custom Pokemon display while moving the common browser path to cheap texture blits

Tests

• Added coverage for sprite key normalization, regional form key resolution, and explicit aspect slot keys