feat(system): multipart backup import via SAF picker — replace path-based import (issue #786) (#839)

* feat(system): multipart backup import via SAF picker — replace path-based import (issue #786)

* fix(system): backup trigger sends required JSON body — 422 fix (BackupRequest contract)

* fix(system): backup download waits for async archive + saves to Downloads

* fix(system): curator min_idle_hours Double parse + single-flight backup download

* fix(system): stream backup download to Downloads — @Streaming + chunked MediaStore write (OOM fix)

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Co-authored-by: M57 <hy4ri@users.noreply.github.com>

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

@@ -425,8 +425,7 @@
     <string name="system_sec_backup">Backup</string>
     <string name="system_sec_restore">Restore from upload</string>
     <string name="system_op_restore_upload">Restore upload</string>
-    <string name="system_op_restore_path_label">Restore from backups path</string>
-    <string name="system_op_restore_path">Restore path</string>
+    <string name="system_op_restore_pick">Choose backup archive</string>
     <string name="system_op_import_confirm_title">Restore full Hermes backup?</string>
     <string name="system_op_import_confirm_desc">This will overwrite your current Hermes configuration, skills, sessions, and data. This cannot be undone.</string>