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/app/(authenticated)/knowledge/page.tsx

@@ -53,8 +53,10 @@ export default function KnowledgePage(): ReactElement {
       filtered = filtered.filter(
         (entry) =>
           entry.title.toLowerCase().includes(query) ||
-          entry.summary?.toLowerCase().includes(query) ||
-          entry.tags.some((tag: { name: string }) => tag.name.toLowerCase().includes(query))
+          (entry.summary?.toLowerCase().includes(query) ?? false) ||
+          entry.tags.some((tag: { name: string }): boolean =>
+            tag.name.toLowerCase().includes(query)
+          )
       );
     }
 
@@ -85,7 +87,7 @@ export default function KnowledgePage(): ReactElement {
   );
 
   // Reset to page 1 when filters change
-  const handleFilterChange = (callback: () => void) => {
+  const handleFilterChange = (callback: () => void): void => {
     callback();
     setCurrentPage(1);
   };
@@ -93,7 +95,7 @@ export default function KnowledgePage(): ReactElement {
   const handleSortChange = (
     newSortBy: "updatedAt" | "createdAt" | "title",
     newSortOrder: "asc" | "desc"
-  ) => {
+  ): void => {
     setSortBy(newSortBy);
     setSortOrder(newSortOrder);
     setCurrentPage(1);