feat(ui): add scan progress and error reporting to UI (#4094)

* feat(scanner): add LastScanError tracking to scanner status

- Introduced LastScanErrorKey constant for error tracking.
- Updated StatusInfo struct to include LastError field.
- Modified scanner logic to store and retrieve last scan error.
- Enhanced ScanStatus response to include error information.
- Updated UI components to display last scan error when applicable.
- Added tests to verify last scan error functionality.

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(scanner): enhance scan status with type and elapsed time tracking

- Added LastScanTypeKey and LastScanStartTimeKey constants for tracking scan type and start time.
- Updated StatusInfo struct to include ScanType and ElapsedTime fields.
- Implemented getScanInfo method to retrieve scan type, elapsed time, and last error.
- Modified scanner logic to store scan type and start time during scans.
- Enhanced ScanStatus response and UI components to display scan type and elapsed time.
- Added formatShortDuration utility for better elapsed time representation.
- Updated activity reducer to handle new scan status fields.

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor(tests): consolidate controller status tests into a single file

- Removed the old controller_status_test.go file.
- Merged relevant tests into the new controller_test.go file for better organization and maintainability.
- Ensured all existing test cases for controller status are preserved and functional.

Signed-off-by: Deluan <deluan@navidrome.org>

* Fix formatting issues

* refactor(scanner): update getScanInfo method documentation

---------

Signed-off-by: Deluan <deluan@navidrome.org>

ui/src/utils/formatters.js

@@ -25,6 +25,26 @@ export const formatDuration = (d) => {
   return `${days > 0 ? days + ':' : ''}${f}`
 }
 
+export const formatShortDuration = (ns) => {
+  // Convert nanoseconds to seconds
+  const seconds = ns / 1e9
+  if (seconds < 1.0) {
+    return '<1s'
+  }
+
+  const hours = Math.floor(seconds / 3600)
+  const minutes = Math.floor((seconds % 3600) / 60)
+  const secs = Math.floor(seconds % 60)
+
+  if (hours > 0) {
+    return `${hours}h${minutes}m`
+  }
+  if (minutes > 0) {
+    return `${minutes}m${secs}s`
+  }
+  return `${secs}s`
+}
+
 export const formatFullDate = (date, locale) => {
   const dashes = date.split('-').length - 1
   let options = {