2649

Added

• PaletteProviding protocol — New PVCoreBridge protocol (PaletteProviding) exposing availablePalettes: [CorePalette], currentPaletteID, and selectPalette(id:) as a structured, type-safe replacement for string-matched CoreActions palette cycling.
• CorePalette model — CorePalette struct with id, displayName, and up to 4 preview PaletteColor values (stored as normalised RGB floats) for swatch rendering.
• GBPalette colour data — All 15 Game Boy DMG palettes now carry actual 4-colour preview data and human-readable display names.
• Gambatte PaletteProviding adoption — PVGBEmulatorCore conforms to PaletteProviding; DMG games expose all 15 palettes, GBC games return an empty list.
• PalettePickerView — New SwiftUI sheet showing a grid of colour swatches; current palette highlighted with a neon selection ring; applies palette live on tap.
• Tile-menu palette tile — PauseTileMenuView shows a paintpalette.fill tile (purple) for cores conforming to PaletteProviding; badge shows the current palette name; the old "Change Palette" cycling action is suppressed when the richer picker is available.
• RetroMenuView palette button — Classic pause menu now shows a "PALETTE: <name>" button in the CORE tab for PaletteProviding cores, opening the same PalettePickerView sheet.