feat(ble): GATT status=5 (FW allowlist bond conflict) UX (cloud-mvp 10c45dc 이식)

FW 팀이 1:1 bond allowlist 정책 추가 예정. 다른 central 과 이미 bond 중인
기기에 붙으면 GATT_INSUFFICIENT_AUTHENTICATION (status=5) 로 거부.

BleManager:
  - bondConflictAddress: MutableStateOf<String?> 신규
  - status=5 감지 시 bondConflictAddress=addr + connectionError="BOND_CONFLICT:$addr"
  - CONNECTED 성공 시 clear

DeviceScanView (ui/views/connection/):
  - 에러 배너 확장 (Column 2단):
    · 안내 문구 (기기 15초 롱프레스로 본딩 삭제)
    · "이 폰의 본딩 정보 초기화" OutlinedButton (unbondAndRemoveAddress)
  - Toast 완료 안내

strings.xml (KR/EN): ble_error_bond_conflict / ble_action_reset_bond / ble_toast_bond_removed

app/src/main/res/values/strings.xml

@@ -379,6 +379,10 @@
     <string name="device_scan_pairing_required_title">Pairing Required</string>
     <string name="device_scan_pairing_required_msg">A Bluetooth pairing request will appear.\nTap \'Pair\', then enter PIN if prompted.</string>
     <string name="device_scan_pairing_required_err">Pairing required. Please pair the device.</string>
+    <!-- FW allowlist bond conflict (GATT status=5) — 2026-08-04 -->
+    <string name="ble_error_bond_conflict">This device is already paired with another app. Long-press the device power button for 15 seconds to clear its pairing, then try again.</string>
+    <string name="ble_action_reset_bond">Reset Pairing (this phone)</string>
+    <string name="ble_toast_bond_removed">Pairing info removed. Please try connecting again.</string>
     <string name="device_scan_back_desc">Back</string>
     <string name="device_scan_warning_desc">Warning</string>
     <string name="device_scan_error_desc">Error</string>