[dashboard] feat: add passkey authentication overlay

[mdabir1203]

Summary

• add a reusable passkey authenticator module that provisions a local credential store and verifies signed challenges
• gate the dashboard orchestration flow behind a passkey check and surface login status in the UI
• layer a passkey prompt overlay and wire up new dependencies, including the refreshed Cargo.lock

Testing

• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace

---

https://chatgpt.com/codex/tasks/task_e_68fe99112f0c8326951fe451d3bc5be1