Reduce all command timeouts to 2-3 seconds max

With 10-second host heartbeat timeout, all command timeouts must be significantly lower to ensure total collection time stays under 10 seconds.

Changed timeouts:
- smartctl: 10s → 3s (critical: multiple drives queried sequentially)
- du: 5s → 2s
- lsblk: 5s → 2s
- systemctl list commands: 5s → 3s
- systemctl show/is-active: 3s → 2s
- docker commands: 5s → 3s
- df, ip commands: 3s → 2s

Total worst-case collection time now capped at more reasonable levels, preventing false host offline alerts from blocking operations.

agent/src/collectors/network.rs

@@ -110,7 +110,7 @@ impl NetworkCollector {
         // Parse VLAN configuration
         let vlan_map = Self::parse_vlan_config();
 
-        match Command::new("timeout").args(["3", "ip", "-j", "addr"]).output() {
+        match Command::new("timeout").args(["2", "ip", "-j", "addr"]).output() {
             Ok(output) if output.status.success() => {
                 let json_str = String::from_utf8_lossy(&output.stdout);