Refactor rendering architecture and replace rasterizer with renderer

- Introduced SoftwareRenderer as a pixel-accurate software rendering backend.
- Removed the obsolete wolf_3d_rasterizer.dart file.
- Created a new wolf_3d_renderer.dart file to centralize rendering exports.
- Updated tests to accommodate the new rendering structure, including pushwall and projection sampling tests.
- Modified the WolfAsciiRenderer and WolfFlutterRenderer to utilize the new SoftwareRenderer.
- Enhanced enemy spawn tests to include new enemy states.

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_dart/test/rendering/projection_sampling_test.dart

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+import 'package:test/test.dart';
+import 'package:wolf_3d_dart/src/rendering/renderer_backend.dart';
+import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
+import 'package:wolf_3d_dart/wolf_3d_engine.dart';
+
+void main() {
+  group('Renderer wall texture sampling', () {
+    test('anchors wall texel sampling to projection height center', () {
+      final renderer = _TestRenderer(customProjectionViewHeight: 40);
+      renderer.configureViewGeometry(width: 64, height: 64, viewHeight: 20);
+
+      // With sceneHeight=40 and columnHeight=20, projected wall spans y=10..30.
+      // Top pixel should sample from top texel row.
+      expect(renderer.wallTexY(10, 20), 0);
+
+      // Bottom visible pixel should sample close to bottom texel row.
+      expect(renderer.wallTexY(29, 20), inInclusiveRange(60, 63));
+    });
+
+    test('keeps legacy behavior when projection height equals view height', () {
+      final renderer = _TestRenderer(customProjectionViewHeight: 20);
+      renderer.configureViewGeometry(width: 64, height: 64, viewHeight: 20);
+
+      // With sceneHeight=viewHeight=20 and columnHeight=20, top starts at y=0.
+      expect(renderer.wallTexY(0, 20), 0);
+      expect(renderer.wallTexY(19, 20), inInclusiveRange(60, 63));
+    });
+  });
+}
+
+class _TestRenderer extends RendererBackend<FrameBuffer> {
+  _TestRenderer({required this.customProjectionViewHeight});
+
+  final int customProjectionViewHeight;
+
+  @override
+  int get projectionViewHeight => customProjectionViewHeight;
+
+  void configureViewGeometry({
+    required int width,
+    required int height,
+    required int viewHeight,
+  }) {
+    this.width = width;
+    this.height = height;
+    this.viewHeight = viewHeight;
+  }
+
+  @override
+  void prepareFrame(WolfEngine engine) {}
+
+  @override
+  void drawWallColumn(
+    int x,
+    int drawStart,
+    int drawEnd,
+    int columnHeight,
+    Sprite texture,
+    int texX,
+    double perpWallDist,
+    int side,
+  ) {}
+
+  @override
+  void drawSpriteStripe(
+    int stripeX,
+    int drawStartY,
+    int drawEndY,
+    int spriteHeight,
+    Sprite texture,
+    int texX,
+    double transformY,
+  ) {}
+
+  @override
+  void drawWeapon(WolfEngine engine) {}
+
+  @override
+  void drawHud(WolfEngine engine) {}
+
+  @override
+  FrameBuffer finalizeFrame() {
+    return FrameBuffer(1, 1);
+  }
+}

packages/wolf_3d_dart/test/rendering/pushwall_renderer_test.dart

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+import 'dart:typed_data';
+
+import 'package:test/test.dart';
+import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
+import 'package:wolf_3d_dart/wolf_3d_engine.dart';
+import 'package:wolf_3d_dart/wolf_3d_input.dart';
+import 'package:wolf_3d_dart/wolf_3d_renderer.dart';
+
+void main() {
+  group('Pushwall rendering', () {
+    test('active pushwall occludes the wall behind it while sliding', () {
+      final wallGrid = _buildGrid();
+      final objectGrid = _buildGrid();
+
+      _fillBoundaries(wallGrid, 2);
+      objectGrid[2][2] = MapObject.playerEast;
+
+      wallGrid[2][4] = 1;
+      objectGrid[2][4] = MapObject.pushwallTrigger;
+
+      wallGrid[2][6] = 2;
+
+      final engine = WolfEngine(
+        data: WolfensteinData(
+          version: GameVersion.shareware,
+          walls: [
+            _solidSprite(1),
+            _solidSprite(1),
+            _solidSprite(2),
+            _solidSprite(2),
+          ],
+          sprites: List.generate(436, (_) => _solidSprite(255)),
+          sounds: [],
+          adLibSounds: [],
+          music: [],
+          vgaImages: [],
+          episodes: [
+            Episode(
+              name: 'Episode 1',
+              levels: [
+                WolfLevel(
+                  name: 'Test Level',
+                  wallGrid: wallGrid,
+                  objectGrid: objectGrid,
+                  musicIndex: 0,
+                ),
+              ],
+            ),
+          ],
+        ),
+        difficulty: Difficulty.medium,
+        startingEpisode: 0,
+        frameBuffer: FrameBuffer(64, 64),
+        input: CliInput(),
+        onGameWon: () {},
+      );
+
+      engine.init();
+
+      final pushwall = engine.pushwallManager.pushwalls['4,2']!;
+      pushwall
+        ..dirX = 1
+        ..dirY = 0
+        ..offset = 0.5;
+      engine.pushwallManager.activePushwall = pushwall;
+
+      final frame = SoftwareRenderer().render(engine);
+      final centerIndex =
+          (frame.height ~/ 2) * frame.width + (frame.width ~/ 2);
+
+      expect(frame.pixels[centerIndex], ColorPalette.vga32Bit[1]);
+      expect(frame.pixels[centerIndex], isNot(ColorPalette.vga32Bit[2]));
+    });
+  });
+}
+
+SpriteMap _buildGrid() => List.generate(64, (_) => List.filled(64, 0));
+
+void _fillBoundaries(SpriteMap grid, int wallId) {
+  for (int i = 0; i < 64; i++) {
+    grid[0][i] = wallId;
+    grid[63][i] = wallId;
+    grid[i][0] = wallId;
+    grid[i][63] = wallId;
+  }
+}
+
+Sprite _solidSprite(int colorIndex) {
+  return Sprite(Uint8List.fromList(List.filled(64 * 64, colorIndex)));
+}