Remove /docs slash command (#36325)

This PR removes the `/docs` slash command.

We never fully shipped this—with it requiring explicit opt-in via a
setting—and it doesn't seem like the feature is needed in an agentic
world.

Release Notes:

- Removed the `/docs` slash command.

crates/agent_ui/src/slash_command_settings.rs

@@ -7,22 +7,11 @@ 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 {