Approve sites' passkey requests from the browser extension

The app comes forward with a prompt to sign in with or save a passkey,
confirmed with the master password (the user verification each use needs).
Asked while locked: unlock, then it continues.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src-tauri/examples/test-host.rs

@@ -1,12 +1,13 @@
 //! Headless stand-in for the desktop app, for end-to-end tests of the browser extension and
 //! `kestrove-nmh`. It runs the same `Broker` as the app over the same IPC endpoint, with an
-//! in-memory vault holding one test login, and plays the user: it approves pairings and saves.
+//! in-memory vault holding one test login, and plays the user: it approves pairings, saves and passkeys.
 //! Never ship this: it auto-approves.
 //!
 //!   KESTROVE_IPC_DIR=/tmp/kv-e2e KESTROVE_TEST_ORIGIN=http://127.0.0.1:8765 \
 //!     cargo run --example test-host
 //!
-//! Prints `READY <endpoint>`, then `PAIRED <words>` and `SAVED <origin> <username>` as they happen.
+//! Prints `READY <endpoint>`, then `PAIRED <words>`, `SAVED <origin> <username>` and
+//! `PASSKEY <create|get> <rp_id> <user>` as they happen.
 
 use std::io::Write;
 use std::sync::Arc;
@@ -14,6 +15,7 @@ use std::thread;
 use std::time::Duration;
 
 use kestrove_desktop::broker::{Broker, PairingStore, PairingView, SaveView, Ui};
+use kestrove_desktop::passkey::{PasskeyKind, PasskeyView};
 use kestrove_desktop::ipc;
 use kv_ffi::{ItemDto, ItemKindDto, VaultCore};
 
@@ -21,6 +23,7 @@ struct Quiet;
 impl Ui for Quiet {
     fn pairing_requested(&self, _: &PairingView) {}
     fn save_requested(&self, _: &SaveView) {}
+    fn passkey_requested(&self, _: &PasskeyView) {}
 }
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
@@ -53,6 +56,15 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                 println!("PAIRED {}", p.words.join(" "));
             }
         }
+        for p in b.pending_passkeys() {
+            if b.resolve_passkey(&p.id, true, None).is_ok() {
+                let (kind, user) = match p.kind {
+                    PasskeyKind::Create => ("create", p.user_name.clone()),
+                    PasskeyKind::Get => ("get", p.choices.first().map(|c| c.user_name.clone()).unwrap_or_default()),
+                };
+                println!("PASSKEY {kind} {} {user}", p.rp_id);
+            }
+        }
         for s in b.pending_saves() {
             if b.resolve_save(&s.id, true).is_ok() {
                 println!("SAVED {} {}", s.origin, s.username);