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/team/TeamSettings.tsx

@@ -10,17 +10,17 @@ interface TeamSettingsProps {
   onDelete: () => Promise<void>;
 }
 
-export function TeamSettings({ team, onUpdate, onDelete }: TeamSettingsProps) {
+export function TeamSettings({ team, onUpdate, onDelete }: TeamSettingsProps): React.JSX.Element {
   const [name, setName] = useState(team.name);
-  const [description, setDescription] = useState(team.description || "");
+  const [description, setDescription] = useState(team.description ?? "");
   const [isEditing, setIsEditing] = useState(false);
   const [isSaving, setIsSaving] = useState(false);
   const [isDeleting, setIsDeleting] = useState(false);
   const [showDeleteConfirm, setShowDeleteConfirm] = useState(false);
 
-  const hasChanges = name !== team.name || description !== (team.description || "");
+  const hasChanges = name !== team.name || description !== (team.description ?? "");
 
-  const handleSave = async () => {
+  const handleSave = async (): Promise<void> => {
     if (!hasChanges) return;
 
     setIsSaving(true);
@@ -29,7 +29,7 @@ export function TeamSettings({ team, onUpdate, onDelete }: TeamSettingsProps) {
       if (name !== team.name) {
         updates.name = name;
       }
-      if (description !== (team.description || "")) {
+      if (description !== (team.description ?? "")) {
         updates.description = description;
       }
       await onUpdate(updates);
@@ -42,13 +42,13 @@ export function TeamSettings({ team, onUpdate, onDelete }: TeamSettingsProps) {
     }
   };
 
-  const handleCancel = () => {
+  const handleCancel = (): void => {
     setName(team.name);
-    setDescription(team.description || "");
+    setDescription(team.description ?? "");
     setIsEditing(false);
   };
 
-  const handleDelete = async () => {
+  const handleDelete = async (): Promise<void> => {
     setIsDeleting(true);
     try {
       await onDelete();