Migrate icon buttons to Button component and simplify size variants

Replace raw <button> elements with Button variant="ghost" in stat-block
panel, toast, player modals. Add icon-sm size variant (h-6 w-6) for
compact contexts. Consolidate text button sizes into a single default
(h-8 px-3), removing the redundant sm variant. Add size prop to
ConfirmButton for consistent sizing.

Button now has three sizes: default (text), icon, icon-sm.

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

apps/web/src/components/action-bar.tsx

@@ -553,9 +553,7 @@ export function ActionBar({
 					</div>
 				)}
 				{!browseMode && nameInput.length >= 2 && !hasSuggestions && (
-					<Button type="submit" size="sm">
-						Add
-					</Button>
+					<Button type="submit">Add</Button>
 				)}
 				{showRollAllInitiative && onRollAllInitiative && (
 					<Button