feat(agent): setup Cargo.toml et structure complète

Initialise la structure de l'agent Rust avec tous les modules stub :
config, payload, metrics (cpu/memory/disk/network/uptime/temperature/smart),
transport (udp/mqtt). Corrige les features sysinfo 0.30 (pas de feature
disk/networks séparées). Compile sans erreurs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent/src/config.rs

@@ -0,0 +1,81 @@
+// stub — implémenté dans la Task 2
+use serde::Deserialize;
+use std::path::Path;
+
+#[derive(Deserialize, Debug, Clone, Default)]
+pub struct Config {
+    pub server: ServerConfig,
+    pub protocols: ProtocolsConfig,
+    #[serde(default)]
+    pub metrics: MetricsConfig,
+}
+
+#[derive(Deserialize, Debug, Clone, Default)]
+pub struct ServerConfig {
+    pub ip: String,
+    pub port: u16,
+}
+
+#[derive(Deserialize, Debug, Clone, Default)]
+pub struct ProtocolsConfig {
+    #[serde(default)]
+    pub udp: UdpConfig,
+    #[serde(default)]
+    pub mqtt: MqttConfig,
+}
+
+#[derive(Deserialize, Debug, Clone, Default)]
+pub struct UdpConfig {
+    #[serde(default)]
+    pub enabled: bool,
+}
+
+#[derive(Deserialize, Debug, Clone, Default)]
+pub struct MqttConfig {
+    #[serde(default)]
+    pub enabled: bool,
+    #[serde(default)]
+    pub host: String,
+    #[serde(default)]
+    pub port: u16,
+    #[serde(default)]
+    pub topic_base: String,
+    #[serde(default)]
+    pub auto_discovery: bool,
+    #[serde(default)]
+    pub birth_message: bool,
+    #[serde(default)]
+    pub last_will: bool,
+}
+
+#[derive(Deserialize, Debug, Clone, Default)]
+pub struct MetricsConfig {
+    #[serde(default)]
+    pub cpu: MetricProto,
+    #[serde(default)]
+    pub memory: MetricProto,
+    #[serde(default)]
+    pub disk: MetricProto,
+    #[serde(default)]
+    pub network: MetricProto,
+    #[serde(default)]
+    pub uptime: MetricProto,
+    #[serde(default)]
+    pub temperature: MetricProto,
+    #[serde(default)]
+    pub smart: MetricProto,
+}
+
+#[derive(Deserialize, Debug, Clone, Default)]
+pub struct MetricProto {
+    #[serde(default)]
+    pub udp: bool,
+    #[serde(default)]
+    pub mqtt: bool,
+}
+
+pub fn load(path: &Path) -> Result<Config, Box<dyn std::error::Error>> {
+    let content = std::fs::read_to_string(path)?;
+    let config: Config = toml::from_str(&content)?;
+    Ok(config)
+}