Polish UI: consistent icon buttons, tooltips, modal backdrop close, and top bar layout

- Standardize icon button sizing (size="icon") and color (text-muted-foreground) across top and bottom bars
- Group bottom bar icon buttons with gap-0 to match top bar style
- Add missing tooltips/aria-labels for stat block viewer, bulk import buttons
- Replace Settings icon with Library for source manager
- Make step forward/back buttons use primary (solid) variant
- Move round badge next to combatant name in center of top bar
- Close player create/edit and management modals on backdrop click

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

apps/web/src/components/__tests__/turn-navigation.test.tsx

@@ -54,11 +54,11 @@ describe("TurnNavigation", () => {
 			expect(container.textContent).not.toContain("—");
 		});
 
-		it("round badge and combatant name are in separate DOM elements", () => {
+		it("round badge and combatant name are siblings in the center area", () => {
 			renderNav();
 			const badge = screen.getByText("R1");
 			const name = screen.getByText("Goblin");
-			expect(badge.parentElement).not.toBe(name.parentElement);
+			expect(badge.parentElement).toBe(name.parentElement);
 		});
 
 		it("updates the round badge when round changes", () => {