style: replace blue accent with gray and mute card badge colors

Switch all interactive UI elements (buttons, focus rings, active tabs,
FAB, links, spinners) from blue to gray to match icon colors for a
more cohesive look. Mute card badge text colors to pastels (blue-400,
green-500, purple-500) to keep the focus on card content.

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

src/client/components/ItemPicker.tsx

@@ -107,7 +107,7 @@ export function ItemPicker({
 													type="checkbox"
 													checked={selectedIds.has(item.id)}
 													onChange={() => handleToggle(item.id)}
-													className="rounded border-gray-300 text-blue-600 focus:ring-blue-500"
+													className="rounded border-gray-300 text-gray-600 focus:ring-gray-400"
 												/>
 												<span className="flex-1 text-sm text-gray-900 truncate">
 													{item.name}
@@ -143,7 +143,7 @@ export function ItemPicker({
 						type="button"
 						onClick={handleDone}
 						disabled={syncItems.isPending}
-						className="flex-1 px-4 py-2 text-sm font-medium text-white bg-blue-600 hover:bg-blue-700 disabled:opacity-50 rounded-lg transition-colors"
+						className="flex-1 px-4 py-2 text-sm font-medium text-white bg-gray-700 hover:bg-gray-800 disabled:opacity-50 rounded-lg transition-colors"
 					>
 						{syncItems.isPending ? "Saving..." : "Done"}
 					</button>