fix: resolve all TypeScript build errors

- Remove unused imports (LoginModal, Zap) and variables
- Fix Language type mismatches across components
- Update HeaderBar interface to use Language type
- Remove unused onLoginClick parameter
- Fix duplicate translation keys by renaming auth steps
- Remove invalid language prop from CommunitySection

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

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

web/src/pages/LandingPage.tsx

@@ -47,7 +47,7 @@ export function LandingPage() {
       <AboutSection language={language} />
       <FeaturesSection language={language} />
       <HowItWorksSection language={language} />
-      <CommunitySection language={language} />
+      <CommunitySection />
 
       {/* CTA */}
       <AnimatedSection backgroundColor='var(--panel-bg)'>