fix: Resolve all ESLint errors and warnings in web package

Fixes all 542 ESLint problems in the web package to achieve 0 errors and 0 warnings.

Changes:
- Fixed 144 issues: nullish coalescing, return types, unused variables
- Fixed 118 issues: unnecessary conditions, type safety, template literals
- Fixed 79 issues: non-null assertions, unsafe assignments, empty functions
- Fixed 67 issues: explicit return types, promise handling, enum comparisons
- Fixed 45 final warnings: missing return types, optional chains
- Fixed 25 typecheck-related issues: async/await, type assertions, formatting
- Fixed JSX.Element namespace errors across 90+ files

All Quality Rails violations resolved. Lint and typecheck both pass with 0 problems.

Files modified: 118 components, tests, hooks, and utilities

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

apps/web/src/components/error-boundary.tsx

@@ -29,16 +29,16 @@ export class ErrorBoundary extends Component<ErrorBoundaryProps, ErrorBoundarySt
     };
   }
 
-  componentDidCatch(error: Error, errorInfo: React.ErrorInfo) {
+  componentDidCatch(error: Error, errorInfo: React.ErrorInfo): void {
     // Log to console for debugging (could also send to error tracking service)
     console.error("Component error:", error, errorInfo);
   }
 
-  handleReload = () => {
+  handleReload = (): void => {
     window.location.reload();
   };
 
-  render() {
+  render(): React.ReactNode {
     if (this.state.hasError) {
       return (
         <div className="min-h-screen flex items-center justify-center bg-gray-50 px-4">