feat: add job worker and duplicate registration check

Job Worker System:
- Add polling-based job worker (max 2 concurrent processors)
- Create monitor_jobs records when videos are registered
- Link videos.job_id to monitor_jobs
- Fix type mismatches (i32 vs i64) for database IDs

Duplicate Registration:
- Check if video already exists before registering
- Return existing video info with already_exists: true
- Use canonical path for UUID computation

USER_DATA_ROOT Configuration:
- Add MOMENTRY_USER_DATA_ROOT environment variable
- UUID computed from relative path (username/filename)
- Ensures consistent UUIDs when data root changes

src/core/storage/uuid.rs

@@ -25,6 +25,41 @@ pub fn compute_uuid_from_path(full_path: &str) -> String {
     compute_uuid(&parent, &filename)
 }
 
+/// Extract relative path from full path given data root
+/// Returns (relative_path, filename)
+pub fn extract_relative_path(full_path: &str, data_root: &str) -> (String, String) {
+    let full_path = PathBuf::from(full_path);
+    let data_root = PathBuf::from(data_root);
+
+    // Canonicalize both paths
+    let full_canonical = full_path.canonicalize().unwrap_or(full_path.clone());
+    let root_canonical = data_root.canonicalize().unwrap_or(data_root.clone());
+
+    // Try to strip the data root prefix
+    let relative = full_canonical
+        .strip_prefix(&root_canonical)
+        .unwrap_or(&full_canonical);
+
+    // Separate into parent directory and filename
+    let filename = relative
+        .file_name()
+        .map(|n| n.to_string_lossy().to_string())
+        .unwrap_or_default();
+
+    let parent = relative
+        .parent()
+        .map(|p| p.to_string_lossy().to_string())
+        .unwrap_or_default();
+
+    (parent, filename)
+}
+
+/// Compute UUID from full path using data root for relative path extraction
+pub fn compute_uuid_from_path_with_root(full_path: &str, data_root: &str) -> String {
+    let (parent, filename) = extract_relative_path(full_path, data_root);
+    compute_uuid(&parent, &filename)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -41,4 +76,26 @@ mod tests {
         let uuid = compute_uuid_from_path("/Users/test/Videos/video.mp4");
         assert_eq!(uuid.len(), 16);
     }
+
+    #[test]
+    fn test_relative_path_extraction() {
+        let (parent, filename) =
+            extract_relative_path("/data/sftpgo/data/demo/video.mp4", "/data/sftpgo/data");
+        assert_eq!(parent, "demo");
+        assert_eq!(filename, "video.mp4");
+    }
+
+    #[test]
+    fn test_uuid_with_data_root() {
+        let uuid1 = compute_uuid_from_path_with_root(
+            "/data/sftpgo/data/demo/video.mp4",
+            "/data/sftpgo/data",
+        );
+        let uuid2 = compute_uuid_from_path_with_root(
+            "/data/sftpgo/data/demo/video.mp4",
+            "/data/sftpgo/data",
+        );
+        assert_eq!(uuid1, uuid2);
+        assert_eq!(uuid1.len(), 16);
+    }
 }