Restyle dark theme with blue-tinted palette, card glow, and rounded surfaces

Shift the dark theme from neutral gray to a richer blue-tinted palette
inspired by CharBuilder-style TTRPG apps. Deeper navy background, steel-blue
card surfaces, and visible blue borders create more depth and visual layering.

- Update design tokens: background, card, border, input, muted colors
- Add card-glow utility (radial gradient + blue box-shadow) for card surfaces
- Add panel-glow utility (top-down gradient) for tall panels like stat blocks
- Apply glow and rounded-lg to all card surfaces, dropdowns, dialogs, toasts
- Give outline buttons a subtle fill instead of transparent background
- Active combatant row now uses full border with glow instead of left accent

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

apps/web/src/components/__tests__/combatant-row.test.tsx

@@ -75,7 +75,7 @@ describe("CombatantRow", () => {
 	it("active combatant gets active border styling", () => {
 		const { container } = renderRow({ isActive: true });
 		const row = container.firstElementChild;
-		expect(row?.className).toContain("border-l-accent");
+		expect(row?.className).toContain("border-accent/40");
 	});
 
 	it("unconscious combatant (currentHp === 0) gets dimmed styling", () => {