Persist dashboard backup metrics separately

plugin/doinst.sh

@@ -12,7 +12,7 @@ fi
 
 mkdir -p "$CONFIG" "$ROOT_PREFIX/run/urbm" "$ROOT_PREFIX/var/lib/urbm"
 if [ -d "$OLD_CONFIG" ]; then
-  for item in config.json runs.json secrets; do
+  for item in config.json runs.json backup-metrics.json secrets; do
     if [ -e "$OLD_CONFIG/$item" ] && [ ! -e "$CONFIG/$item" ]; then
       cp -a "$OLD_CONFIG/$item" "$CONFIG/$item"
     fi

plugin/urbm.plg

@@ -2,13 +2,18 @@
 <!DOCTYPE PLUGIN [
 <!ENTITY name "urbm">
 <!ENTITY author "Michael Roll">
-<!ENTITY version "2026.07.13.r008">
+<!ENTITY version "2026.07.13.r009">
 <!ENTITY pluginURL "https://git.casaderoll.de/michael/URBM/raw/branch/main/dist/urbm.plg">
 <!ENTITY packageURL "https://git.casaderoll.de/michael/URBM/raw/branch/main/dist/urbm-&version;-x86_64-1.txz">
 <!ENTITY packageSHA256 "REPLACE_DURING_RELEASE">
 ]>
 <PLUGIN name="&name;" author="&author;" version="&version;" pluginURL="&pluginURL;" min="7.0.0" support="https://git.casaderoll.de/michael/URBM/issues" icon="urbm.png">
   <CHANGES>
+### 2026.07.13.r009
+- Store completed-backup chart measurements independently in `backup-metrics.json` so clearing activities no longer erases the dashboard history.
+- Migrate existing successful backup runs into the new durable metric history automatically and expose them through a dedicated read-only API.
+- Keep up to 5,000 compact measurements and clarify in the delete dialog that dashboard chart data is preserved.
+
 ### 2026.07.13.r008
 - Remove the nested vertical scrollbar from the snapshot repository browser and use the normal Unraid page scroll.
 - Keep lazy folder loading and cap deep tree indentation so long paths remain usable on desktop and mobile.