feat(daemon): GetPendingStatus D-Bus method + 2 integration tests

Drops the #[allow(dead_code)] on AppState::get_pending_status — it's now
called from the D-Bus dispatch. Two new p2p tests cover the absent and
the round-trip cases.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

daemon/src/state.rs

@@ -259,7 +259,6 @@ impl AppState {
         Ok(self.pending.get(user)?.is_some())
     }
 
-    #[allow(dead_code)] // wired through D-Bus in Task 5.
     pub async fn get_pending_status(&self, user: &str) -> Result<PendingStatus, StateError> {
         match self.pending.get(user)? {
             Some(flag) => Ok(PendingStatus { present: true, flag }),