Add comprehensive timeouts to all blocking system commands

Fixes random host disconnections caused by blocking operations preventing timely ZMQ packet transmission.

Changes:
- Add run_command_with_timeout() wrapper using tokio for async command execution
- Apply 10s timeout to smartctl (prevents 30+ second hangs on failing drives)
- Apply 5s timeout to du, lsblk, systemctl list commands
- Apply 3s timeout to systemctl show/is-active, df, ip commands
- Apply 2s timeout to hostname command
- Use system 'timeout' command for sync operations where async not needed

Critical fixes:
- smartctl: Failing drives could block for 30+ seconds per drive
- du: Large directories (Docker, PostgreSQL) could block 10-30+ seconds
- systemctl/docker: Commands could block indefinitely during system issues

With 1-second collection interval and 10-second heartbeat timeout, any blocking operation >10s causes false "host offline" alerts. These timeouts ensure collection completes quickly even during system degradation.

agent/src/collectors/disk.rs

@@ -112,9 +112,12 @@ impl DiskCollector {
 
     /// Get block devices and their mount points using lsblk
     async fn get_mount_devices(&self) -> Result<HashMap<String, String>, CollectorError> {
-        let output = Command::new("lsblk")
-            .args(&["-rn", "-o", "NAME,MOUNTPOINT"])
-            .output()
+        use super::run_command_with_timeout;
+
+        let mut cmd = Command::new("lsblk");
+        cmd.args(&["-rn", "-o", "NAME,MOUNTPOINT"]);
+
+        let output = run_command_with_timeout(cmd, 5).await
             .map_err(|e| CollectorError::SystemRead {
                 path: "block devices".to_string(),
                 error: e.to_string(),
@@ -186,8 +189,8 @@ impl DiskCollector {
 
     /// Get filesystem info for a single mount point
     fn get_filesystem_info(&self, mount_point: &str) -> Result<(u64, u64), CollectorError> {
-        let output = Command::new("df")
-            .args(&["--block-size=1", mount_point])
+        let output = std::process::Command::new("timeout")
+            .args(&["2", "df", "--block-size=1", mount_point])
             .output()
             .map_err(|e| CollectorError::SystemRead {
                 path: format!("df {}", mount_point),
@@ -413,6 +416,8 @@ impl DiskCollector {
 
     /// Get SMART data for a single drive
     async fn get_smart_data(&self, drive_name: &str) -> Result<SmartData, CollectorError> {
+        use super::run_command_with_timeout;
+
         // Use direct smartctl (no sudo) - service has CAP_SYS_RAWIO and CAP_SYS_ADMIN capabilities
         // For NVMe drives, specify device type explicitly
         let mut cmd = Command::new("smartctl");
@@ -422,7 +427,7 @@ impl DiskCollector {
             cmd.args(&["-a", &format!("/dev/{}", drive_name)]);
         }
 
-        let output = cmd.output()
+        let output = run_command_with_timeout(cmd, 10).await
             .map_err(|e| CollectorError::SystemRead {
                 path: format!("SMART data for {}", drive_name),
                 error: e.to_string(),
@@ -757,9 +762,9 @@ impl DiskCollector {
 
     /// Get drive information for a mount path
     fn get_drive_info_for_path(&self, path: &str) -> anyhow::Result<PoolDrive> {
-        // Use lsblk to find the backing device
-        let output = Command::new("lsblk")
-            .args(&["-rn", "-o", "NAME,MOUNTPOINT"])
+        // Use lsblk to find the backing device with timeout
+        let output = Command::new("timeout")
+            .args(&["5", "lsblk", "-rn", "-o", "NAME,MOUNTPOINT"])
             .output()
             .map_err(|e| anyhow::anyhow!("Failed to run lsblk: {}", e))?;