refactor: remove lessons not covered in HdM lectures

Keep only modules covered in 223015c lectures:
- HTML: Elements, Forms, Validation, Details, Progress, Tables, SVG, Marquee
- CSS: Basic Selectors, Box Model, Units & Variables, Flexbox, Responsive, Transitions

Remove:
- Advanced Selectors
- Tailwind
- HTML: Datalist, Data Attributes, Dialog, Fieldset, Figure

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/unit/lessons.test.js

@@ -17,11 +17,8 @@ describe("Lessons Config Module", () => {
 			expect(moduleIds).toContain("html-forms-validation");
 			// CSS modules
 			expect(moduleIds).toContain("css-basic-selectors");
-			expect(moduleIds).toContain("css-advanced-selectors");
 			expect(moduleIds).toContain("box-model");
 			expect(moduleIds).toContain("flexbox");
-			// Tailwind
-			expect(moduleIds).toContain("tailwind-basics");
 		});
 
 		test("should have mode set on each lesson", async () => {