Remove assistant crate (#30168)

This PR removes the `assistant` crate, as it is no longer used.

Release Notes:

- N/A

crates/agent/src/slash_command_settings.rs

@@ -0,0 +1,49 @@
+use anyhow::Result;
+use gpui::App;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+use settings::{Settings, SettingsSources};
+
+/// Settings for slash commands.
+#[derive(Deserialize, Serialize, Debug, Default, Clone, JsonSchema)]
+pub struct SlashCommandSettings {
+    /// Settings for the `/docs` slash command.
+    #[serde(default)]
+    pub docs: DocsCommandSettings,
+    /// Settings for the `/cargo-workspace` slash command.
+    #[serde(default)]
+    pub cargo_workspace: CargoWorkspaceCommandSettings,
+}
+
+/// Settings for the `/docs` slash command.
+#[derive(Deserialize, Serialize, Debug, Default, Clone, JsonSchema)]
+pub struct DocsCommandSettings {
+    /// Whether `/docs` is enabled.
+    #[serde(default)]
+    pub enabled: bool,
+}
+
+/// Settings for the `/cargo-workspace` slash command.
+#[derive(Deserialize, Serialize, Debug, Default, Clone, JsonSchema)]
+pub struct CargoWorkspaceCommandSettings {
+    /// Whether `/cargo-workspace` is enabled.
+    #[serde(default)]
+    pub enabled: bool,
+}
+
+impl Settings for SlashCommandSettings {
+    const KEY: Option<&'static str> = Some("slash_commands");
+
+    type FileContent = Self;
+
+    fn load(sources: SettingsSources<Self::FileContent>, _cx: &mut App) -> Result<Self> {
+        SettingsSources::<Self::FileContent>::json_merge_with(
+            [sources.default]
+                .into_iter()
+                .chain(sources.user)
+                .chain(sources.server),
+        )
+    }
+
+    fn import_from_vscode(_vscode: &settings::VsCodeSettings, _current: &mut Self::FileContent) {}
+}