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/InviteMember.tsx

@@ -13,7 +13,7 @@ export function InviteMember({ onInvite }: InviteMemberProps) {
   const [isInviting, setIsInviting] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
-  const handleSubmit = async (e: React.FormEvent) => {
+  const handleSubmit = async (e: React.SyntheticEvent<HTMLFormElement>) => {
     e.preventDefault();
     setError(null);
 
@@ -33,7 +33,7 @@ export function InviteMember({ onInvite }: InviteMemberProps) {
       setEmail("");
       setRole(WorkspaceMemberRole.MEMBER);
       alert("Invitation sent successfully!");
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to invite member:", error);
       setError(
         error instanceof Error ? error.message : "Failed to send invitation. Please try again."