Feature/connect employee card tile to backend

[sihaosimonz]

• Fetch employee data from the backend endpoint
• Ensure loading skeletons appear before data is fetched
• On successful fetch, replace skeletons with populated cards
• Support live re-rendering if filters or search terms change.

[Thomasbenissan]

Hey Simon, nice work connecting the directory to the backend. I went through the PR and made a round of fixes directly on the branch:

1. Renamed role to jobTitle
   The existing position field holds auth-tier values ("Manager", "HR", "Employee") used across evals/HR services. Having a separate role field next to it is confusing. jobTitle is unambiguous. Updated across schema, seed, API, types, filters, and components.

2. Removed email from UserMetadata, now fetched from Supabase Auth
   Email already lives in Supabase's auth.users table. Duplicating it creates sync risk. The API route now fetches emails via auth.admin.listUsers() and zips them into the response.

3. Removed online and away fields
   Static booleans in Postgres won't reflect real presence.

4. Fixed DirectoryApiEmployee type
   The interface declared is_admin and is_hr, but the API never returns them. They'd be undefined at runtime. Removed so the type matches the actual response.

5. Updated shared UserMetadata type in src/types/auth.ts
   Added the new fields (department, jobTitle, bio, etc.) so the rest of the app is aware of them.

6. Added error state for fetch failure
   Previously a failed fetch just showed "No employees found." Now shows a proper error message.

7. Changed birthday from String to DateTime? @db.Date
   Matches the rest of the schema. The API formats it to YYYY-MM-DD for the frontend.

8. Restored "Results:" heading in ResultsGrid
   The skeleton refactor accidentally dropped the heading and outer wrapper padding.

9. Migration needed
   Please run npx prisma migrate dev --name add-directory-fields with your local DB up and include the generated migration before merging.