feat(01-03): add QWERTZ keyboard renderer with finger colors and animations

- Full QWERTZ keyboard with DE and CH layout support
- Finger color mapping for all keys per spec section 8.3
- renderKeyboard, highlightKey, pressKey, updateKeyboardForLevel exports
- CSS: pulse animation for target key, press animation on keydown
- Inactive keys grayed at 0.5 opacity, active keys with finger colors

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/game/levels.test.ts

@@ -7,39 +7,39 @@ describe("levels", () => {
 	});
 
 	it("Level 1 newKeys = ['f', 'j', ' ']", () => {
-		expect(levels[0].newKeys).toEqual(["f", "j", " "]);
+		expect(levels[0]!.newKeys).toEqual(["f", "j", " "]);
 	});
 
 	it("Level 2 newKeys = ['d', 'k']", () => {
-		expect(levels[1].newKeys).toEqual(["d", "k"]);
+		expect(levels[1]!.newKeys).toEqual(["d", "k"]);
 	});
 
 	it("Level 3 newKeys = ['s', 'l']", () => {
-		expect(levels[2].newKeys).toEqual(["s", "l"]);
+		expect(levels[2]!.newKeys).toEqual(["s", "l"]);
 	});
 
 	it("Level 4 newKeys = ['a', 'ö']", () => {
-		expect(levels[3].newKeys).toEqual(["a", "ö"]);
+		expect(levels[3]!.newKeys).toEqual(["a", "ö"]);
 	});
 
 	it("Level 5 newKeys = ['g', 'h']", () => {
-		expect(levels[4].newKeys).toEqual(["g", "h"]);
+		expect(levels[4]!.newKeys).toEqual(["g", "h"]);
 	});
 
 	it("Level 6 newKeys = ['e', 'i']", () => {
-		expect(levels[5].newKeys).toEqual(["e", "i"]);
+		expect(levels[5]!.newKeys).toEqual(["e", "i"]);
 	});
 
 	it("Level 3 allKeys includes all keys from levels 1-3", () => {
 		const expected = ["f", "j", " ", "d", "k", "s", "l"];
 		for (const key of expected) {
-			expect(levels[2].allKeys).toContain(key);
+			expect(levels[2]!.allKeys).toContain(key);
 		}
-		expect(levels[2].allKeys).toHaveLength(expected.length);
+		expect(levels[2]!.allKeys).toHaveLength(expected.length);
 	});
 
 	it("Level 6 allKeys contains 13 keys", () => {
-		expect(levels[5].allKeys).toHaveLength(13);
+		expect(levels[5]!.allKeys).toHaveLength(13);
 		const expected = [
 			"f",
 			"j",
@@ -56,7 +56,7 @@ describe("levels", () => {
 			"i",
 		];
 		for (const key of expected) {
-			expect(levels[5].allKeys).toContain(key);
+			expect(levels[5]!.allKeys).toContain(key);
 		}
 	});