feat: refactor parsing and scanning logic for test files

- Updated `parseFilename` to `parseTargetFilename` and modified its return structure to include `test_id` instead of `file_id`.
- Introduced `parseResultFilename` to extract `test_id` and `device` from result file names.
- Enhanced `fullScan` to separately handle target and results directories, improving clarity and functionality.
- Updated database interactions to use `test_id` instead of `file_id` across various modules.
- Added a new `/rescan` endpoint to trigger a full scan of target and results directories.
- Improved logging and error handling throughout the scanning process.
- Introduced `parseTputRssi` to extract throughput and RSSI data from log files.

server/watcher.js

@@ -68,10 +68,10 @@ function startWatching(targetDir, resultsDir) {
     if (path.normalize(dirPath) === path.normalize(resultsDir)) return;
     const dirName = path.basename(dirPath);
     const segs   = dirName.split(/[_\-]/);
-    const file_id = segs.find(s => /^R\d+[A-Z0-9]+$/i.test(s)) || null;
+    const test_id = segs.find(s => /^R\d+[A-Z0-9]+$/i.test(s)) || null;
     const device  = segs.find(s => /^CGW\d+$/i.test(s))        || null;
-    if (file_id) {
-      resetByFileIdAndDevice(file_id, device);
+    if (test_id) {
+      resetByFileIdAndDevice(test_id, device);
       broadcast({ type: 'update' });
     }
   });