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/lib/hooks/useLayout.ts

@@ -35,7 +35,7 @@ export function useLayout() {
       if (storedLayoutId) {
         setCurrentLayoutId(storedLayoutId);
       }
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to load layouts from localStorage:", error);
     } finally {
       setIsLoading(false);
@@ -48,7 +48,7 @@ export function useLayout() {
       try {
         localStorage.setItem(STORAGE_KEY, JSON.stringify(layouts));
         localStorage.setItem(`${STORAGE_KEY}-current`, currentLayoutId);
-      } catch (_error) {
+      } catch (error) {
         console.error("Failed to save layouts to localStorage:", error);
       }
     }
@@ -215,7 +215,7 @@ export function useWorkspaceId(): string | null {
       if (stored) {
         setWorkspaceId(stored);
       }
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to load workspace ID from localStorage:", error);
     }
   }, []);