fix: p12 import — pick file first, then password (matches normal usage)

The Choose .p12 button was gated on a non-blank password, which forced users
to type the password before selecting the file. Now the file picker is always
available; after selection the filename is shown, then the password field and
an Import button appear.

core/presentation/src/main/res/values-zh/strings.xml

@@ -202,6 +202,7 @@
     <string name="prefs_lotw_upload_cert_hint">导入你的 TrustedQSL .p12 证书（与 TQSL 同款）用于签名上传通联。密码仅加密保存在手机本地。</string>
     <string name="prefs_lotw_upload_password">证书密码</string>
     <string name="prefs_lotw_upload_import">选择 .p12 文件</string>
+    <string name="prefs_lotw_upload_import_confirm">导入</string>
     <string name="prefs_lotw_upload_cert_info">%1$s · DXCC %2$d · 有效期至 %3$s</string>
     <string name="prefs_lotw_upload_remove">移除证书</string>
     <string name="prefs_lotw_upload_station_title">台址</string>

core/presentation/src/main/res/values/strings.xml

@@ -233,6 +233,7 @@
     <string name="prefs_lotw_upload_cert_hint">Import your TrustedQSL .p12 certificate (same one you use in TQSL) to sign and upload QSOs. The password is stored encrypted on this device only.</string>
     <string name="prefs_lotw_upload_password">Certificate password</string>
     <string name="prefs_lotw_upload_import">Choose .p12 file</string>
+    <string name="prefs_lotw_upload_import_confirm">Import</string>
     <string name="prefs_lotw_upload_cert_info">%1$s · DXCC %2$d · expires %3$s</string>
     <string name="prefs_lotw_upload_remove">Remove certificate</string>
     <string name="prefs_lotw_upload_station_title">Station location</string>