config/schema: add serde default to AutonomyConfig (#3691)

Co-authored-by: Argenis <theonlyhennygod@gmail.com>

src/config/schema.rs

@@ -3451,6 +3451,7 @@ impl Default for WebhookAuditConfig {
 /// Controls what the agent is allowed to do: shell commands, filesystem access,
 /// risk approval gates, and per-policy budgets.
 #[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
+#[serde(default)]
 pub struct AutonomyConfig {
     /// Autonomy level: `read_only`, `supervised` (default), or `full`.
     pub level: AutonomyLevel,