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/knowledge/EntryList.tsx

@@ -16,7 +16,7 @@ export function EntryList({
   currentPage,
   totalPages,
   onPageChange,
-}: EntryListProps) {
+}: EntryListProps): React.JSX.Element {
   if (isLoading) {
     return (
       <div className="flex justify-center items-center p-12">
@@ -26,7 +26,7 @@ export function EntryList({
     );
   }
 
-  if (!entries || entries.length === 0) {
+  if (entries.length === 0) {
     return (
       <div className="text-center p-12 bg-white rounded-lg shadow-sm border border-gray-200">
         <BookOpen className="w-12 h-12 text-gray-400 mx-auto mb-3" />
@@ -76,7 +76,7 @@ export function EntryList({
 
               if (showEllipsisBefore || showEllipsisAfter) {
                 return (
-                  <span key={`ellipsis-${page}`} className="px-2 text-gray-500">
+                  <span key={`ellipsis-${String(page)}`} className="px-2 text-gray-500">
                     ...
                   </span>
                 );