agent: Add setting to control terminal card expanded state (#34061)

Similar to https://github.com/zed-industries/zed/pull/34040, this PR
allows to control via settings whether the terminal card in the agent
panel should be expanded. It is set to true by default.

Release Notes:

- agent: Added a setting to control whether terminal cards are expanded
in the agent panel, thus showing or hiding the full command output.

crates/agent_settings/src/agent_settings.rs

@@ -68,6 +68,7 @@ pub struct AgentSettings {
     pub preferred_completion_mode: CompletionMode,
     pub enable_feedback: bool,
     pub expand_edit_card: bool,
+    pub expand_terminal_card: bool,
 }
 
 impl AgentSettings {
@@ -296,6 +297,10 @@ pub struct AgentSettingsContent {
     ///
     /// Default: true
     expand_edit_card: Option<bool>,
+    /// Whether to have terminal cards in the agent panel expanded, showing the whole command output.
+    ///
+    /// Default: true
+    expand_terminal_card: Option<bool>,
 }
 
 #[derive(Clone, Copy, Debug, Serialize, Deserialize, JsonSchema, PartialEq, Default)]
@@ -447,6 +452,10 @@ impl Settings for AgentSettings {
             );
             merge(&mut settings.enable_feedback, value.enable_feedback);
             merge(&mut settings.expand_edit_card, value.expand_edit_card);
+            merge(
+                &mut settings.expand_terminal_card,
+                value.expand_terminal_card,
+            );
 
             settings
                 .model_parameters