feat: apply RichText to content sections and experience cards

ExperienceCard description switches from a plain <p> to RichText so
rich-text HTML from PocketBase renders correctly. BioSection and
IntroSection drop the prose class overrides — RichText handles
typography consistently.

src/entities/experience/ui/ExperienceCard/ExperienceCard.test.tsx

@@ -50,10 +50,10 @@ describe('ExperienceCard', () => {
       expect(company).toHaveClass('opacity-80');
     });
 
-    it('description paragraph has text-base and max-w-[700px]', () => {
+    it('description renders via RichText with rich-text class', () => {
       render(<ExperienceCard {...DEFAULT_PROPS} />);
       const desc = screen.getByText('Built scalable frontend systems.');
-      expect(desc).toHaveClass('text-base', 'max-w-[700px]');
+      expect(desc.closest('.rich-text')).toBeInTheDocument();
     });
 
     it('card has brutal-border class (from Card component)', () => {