feat(agama-flow): Implement passkey adoption flows and login UX improvements.

Prioritized GitHub Issues for Janssen Passkey Enhancement Spec ([wiki](https://github.com/JanssenProject/jans/wiki/(Draft-proposal):-Janssen-Passkey-Enhancement-Spec)), issue no: 2

**Description:**
Introduce key features to increase passkey adoption and improve login experience using Agama and UI enhancements.

**Tasks**

- [ ] Create new Agama project: agama-passkey-adopt
- Post-login prompt encouraging users to create passkeys
- Triggered after successful password login

- [ ] Add Conditional UI support to login form (`main.ftlh`)
- Add:
`autocomplete="username webauthn"`
- Enables browser-native passkey suggestions

- [ ] Create new Agama project: agama-passkey-first
- Implement passkey-first (identifier-first) login flow
- If passkey exists → use passkey
- Else → fallback to password

- [ ] AdminUI: Add Passkey Adoption Metrics panel
- Metrics:
- Total users
- Passkey users
- Adoption rate (%)
- Passkey vs password logins