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/dashboard/DomainOverviewWidget.tsx

@@ -6,7 +6,10 @@ interface DomainOverviewWidgetProps {
   isLoading: boolean;
 }
 
-export function DomainOverviewWidget({ tasks, isLoading }: DomainOverviewWidgetProps) {
+export function DomainOverviewWidget({
+  tasks,
+  isLoading,
+}: DomainOverviewWidgetProps): React.JSX.Element {
   if (isLoading) {
     return (
       <div className="bg-white rounded-lg shadow-sm border border-gray-200 p-6">
@@ -25,7 +28,15 @@ export function DomainOverviewWidget({ tasks, isLoading }: DomainOverviewWidgetP
     highPriority: tasks.filter((t) => t.priority === TaskPriority.HIGH).length,
   };
 
-  const StatCard = ({ label, value, color }: { label: string; value: number; color: string }) => (
+  const StatCard = ({
+    label,
+    value,
+    color,
+  }: {
+    label: string;
+    value: number;
+    color: string;
+  }): React.JSX.Element => (
     <div className={`p-4 rounded-lg bg-gradient-to-br ${color}`}>
       <div className="text-3xl font-bold text-white mb-1">{value}</div>
       <div className="text-sm text-white/90">{label}</div>