Add pre-commit hooks for linting and formatting

Set up pre-commit framework with ruff (backend) and ESLint/Prettier/tsc
(frontend) hooks to catch issues locally before CI. Auto-format all
frontend files with Prettier to comply with the new check.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/ShinyBox.tsx

@@ -22,7 +22,9 @@ export function ShinyBox({ encounters, onEncounterClick }: ShinyBoxProps) {
             <PokemonCard
               key={enc.id}
               encounter={enc}
-              onClick={onEncounterClick ? () => onEncounterClick(enc) : undefined}
+              onClick={
+                onEncounterClick ? () => onEncounterClick(enc) : undefined
+              }
             />
           ))}
         </div>