feat: Implement configuration management module

- Create Config struct with serde support for JSON parsing
- Define DisplayConfig for UI toggle options
- Define AlertThresholds for monitoring alerts
- Implement Default trait for sensible defaults
- Add load() method to read config from file
- Support same config format as Python version for compatibility

src/config.rs

@@ -0,0 +1,59 @@
+use serde::{Deserialize, Serialize};
+use std::fs;
+use std::path::Path;
+use anyhow::Result;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Config {
+    pub update_interval: u64,
+    pub display: DisplayConfig,
+    pub process_limit: usize,
+    pub alert_thresholds: AlertThresholds,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DisplayConfig {
+    pub show_cpu: bool,
+    pub show_memory: bool,
+    pub show_disk: bool,
+    pub show_network: bool,
+    pub show_processes: bool,
+    pub show_temperatures: bool,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AlertThresholds {
+    pub cpu_percent: f32,
+    pub memory_percent: f32,
+    pub disk_percent: f32,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Config {
+            update_interval: 5,
+            display: DisplayConfig {
+                show_cpu: true,
+                show_memory: true,
+                show_disk: true,
+                show_network: true,
+                show_processes: true,
+                show_temperatures: true,
+            },
+            process_limit: 5,
+            alert_thresholds: AlertThresholds {
+                cpu_percent: 80.0,
+                memory_percent: 85.0,
+                disk_percent: 90.0,
+            },
+        }
+    }
+}
+
+impl Config {
+    pub fn load<P: AsRef<Path>>(path: P) -> Result<Self> {
+        let contents = fs::read_to_string(path)?;
+        let config: Config = serde_json::from_str(&contents)?;
+        Ok(config)
+    }
+}