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/db/redis_client.rs

@@ -336,7 +336,7 @@ impl RedisClient {
     pub async fn update_worker_job_status(
         &self,
         uuid: &str,
-        job_id: i64,
+        job_id: i32,
         status: &str,
         current_processor: Option<&str>,
         progress: i32,
@@ -401,7 +401,7 @@ impl RedisClient {
         }
 
         let status: String = conn.hget(&key, "status").await?;
-        let job_id: i64 = conn.hget(&key, "job_id").await?;
+        let job_id: i32 = conn.hget(&key, "job_id").await?;
         let current_processor: String = conn.hget(&key, "current_processor").await?;
         let progress_current: i32 = conn.hget(&key, "progress_current").await?;
         let progress_total: i32 = conn.hget(&key, "progress_total").await?;
@@ -538,7 +538,7 @@ pub struct AnomalyAlertMessage {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct WorkerJobStatus {
     pub uuid: String,
-    pub job_id: i64,
+    pub job_id: i32,
     pub status: String,
     pub current_processor: String,
     pub progress_current: i32,
@@ -549,7 +549,7 @@ pub struct WorkerJobStatus {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct WorkerJobInfo {
     pub uuid: String,
-    pub job_id: i64,
+    pub job_id: i32,
     pub status: String,
     pub progress_current: i32,
     pub progress_total: i32,