Add disk wear monitoring and fix storage overflow display

- Add disk wear percentage collection from SMART data in backup script
- Add backup_disk_wear_percent metric to backup collector with thresholds
- Display wear percentage in backup widget disk section
- Fix storage section overflow handling to use consistent "X more below" logic
- Update maintenance mode to return pending status instead of unknown

Cargo.lock

@@ -279,7 +279,7 @@ checksum = "a1d728cc89cf3aee9ff92b05e62b19ee65a02b5702cff7d5a377e32c6ae29d8d"
 
 [[package]]
 name = "cm-dashboard"
-version = "0.1.95"
+version = "0.1.96"
 dependencies = [
  "anyhow",
  "chrono",
@@ -301,7 +301,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-agent"
-version = "0.1.95"
+version = "0.1.96"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -324,7 +324,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-shared"
-version = "0.1.95"
+version = "0.1.96"
 dependencies = [
  "chrono",
  "serde",