fix: refine announcement inject slot-busy detection

Block inject only on external QSO (RX active, TX in hangtime) while
still allowing dynamic UA and active-bridge slots used for synthetic PTT.

src/adn_server/application/voice_use_cases.py

@@ -127,20 +127,23 @@ class VoiceUseCases:
         from .routing.helpers import master_dynamic_tg_slots, master_slot_holds_server_broadcast
         from .server_voice import all_server_voice_ids
 
-        if slot.get("RX_TYPE") != HBPF_SLT_VTERM or slot.get("TX_TYPE") != HBPF_SLT_VTERM:
-            if master_slot_holds_server_broadcast(
-                slot,
-                time.time(),
-                server_voice_rf_srcs=all_server_voice_ids(self._config),
-            ):
-                return False
+        if master_slot_holds_server_broadcast(
+            slot,
+            time.time(),
+            server_voice_rf_srcs=all_server_voice_ids(self._config),
+        ):
+            return False
+        # External QSO on RX while slot is in hangtime — defer announcement inject.
+        if slot.get("RX_TYPE") != HBPF_SLT_VTERM and slot.get("TX_TYPE") == HBPF_SLT_VTERM:
             return True
         if wire_ts in master_dynamic_tg_slots(sys_cfg, int(tg)):
             return False
         ptt_system = self._announcement_ptt_system or ""
         if wire_ts in self._active_bridge_slots_for_tg(tg, ptt_system):
             return False
-        return False
+        if slot.get("RX_TYPE") == HBPF_SLT_VTERM and slot.get("TX_TYPE") == HBPF_SLT_VTERM:
+            return False
+        return True
 
     def _inject_ptt_slot_order(self, tg: int, sys_cfg: dict[str, Any]) -> list[int]:
         """Prefer the RF slot where ``tg`` is already a dynamic UA session."""