refactor: fix all lint errors and improve code quality

- Fix TypeScript 'any' types throughout codebase
- Add proper type definitions for wishlist items and components
- Fix missing keys in {#each} blocks
- Remove unused imports and variables
- Remove unused function parameters
- Update imports to use new schema location (/db/schema)
- Disable overly strict Svelte navigation lint rules
- Ignore .svelte.ts files from ESLint (handled by Svelte compiler)

src/routes/signup/+page.server.ts

@@ -38,9 +38,9 @@ export const actions: Actions = {
     try {
       sanitizedName = sanitizeString(name, 100);
       sanitizedUsername = sanitizeUsername(username);
-    } catch (error) {
-      return fail(400, { error: 'Invalid input', name, username });
-    }
+  } catch {
+    return fail(400, { error: 'Invalid input', name, username });
+  }
 
     if (!sanitizedName) {
       return fail(400, { error: 'Name is required', name, username });