fix: Resolve web package lint and typecheck errors

Fixes ESLint and TypeScript errors in web package to pass CI checks:

- Fixed all Quality Rails violations (14 explicit any types)
- Fixed deprecated React event types (FormEvent → SyntheticEvent)
- Fixed 26 TypeScript errors (Promise types, test mocks, HTMLElement assertions)
- Added vitest DOM matcher type definitions
- Fixed unused variables and empty functions
- Resolved 43+ additional lint errors

Typecheck: ✅ 0 errors
Lint: 542 remaining (non-blocking in CI)

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

apps/web/src/components/workspace/MemberList.tsx

@@ -37,7 +37,7 @@ export function MemberList({
   const handleRoleChange = async (userId: string, newRole: WorkspaceMemberRole) => {
     try {
       await onRoleChange(userId, newRole);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to change role:", error);
       alert("Failed to change member role");
     }
@@ -50,7 +50,7 @@ export function MemberList({
 
     try {
       await onRemove(userId);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to remove member:", error);
       alert("Failed to remove member");
     }