chore(agent-host): drop local managedSettings shim for published SDK type

Remove the temporary ICopilotManagedSettingsSdk mirror and return a plain
ResumeSessionConfig from _buildSessionConfig. The SDK #2139 generated types
add `managedSettings` to the session config, so VS Code no longer needs a
local additive type to forward enterprise-policy-derived permissions.

The conditional `managedSettings` spread is unchanged: it compiles today
(spread properties skip excess-property checks) and gains full static type
safety once the refreshed @github/copilot-sdk carrying #2139 is picked up on
rebase. No caller reads config.managedSettings, so narrowing the return type
is safe.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: c111c62a-eff3-4ff6-bb8a-8436a1b4babe

Author: joshspicer

src/vs/platform/agentHost/node/copilot/copilotSessionLauncher.ts

@@ -82,18 +82,6 @@ type McpAuthContext = Parameters<McpAuthHandler>[1];
 type McpAuthResponse = Awaited<ReturnType<McpAuthHandler>>;
 type PreToolUseHookInput = Parameters<NonNullable<SessionHooks['onPreToolUse']>>[0];
 type PostToolUseHookInput = Parameters<NonNullable<SessionHooks['onPostToolUse']>>[0];
-/**
- * Local mirror of the SDK's `managedSettings` session-config field, scoped to
- * the `permissions` object VS Code populates. The currently published SDK
- * exposes `enableManagedSettings` but not `managedSettings`; this precise
- * additive type lets VS Code forward enterprise-policy-derived permissions
- * until the SDK publishes the field.
- * Mirrors the local-type precedent used for `ICopilotRuntimeManagedSettingsSdk`
- * in copilotAgent.ts.
- */
-interface ICopilotManagedSettingsSdk {
-	readonly permissions?: IManagedPermissions;
-}
 
 /**
  * Immutable snapshot of the active client's structural contributions at
@@ -594,7 +582,7 @@ export class CopilotSessionLauncher implements ICopilotSessionLauncher {
 		}
 	}
 
-	private async _buildSessionConfig(plan: CopilotSessionLaunchPlan, runtime: ICopilotSessionRuntime): Promise<ResumeSessionConfig & { managedSettings?: ICopilotManagedSettingsSdk }> {
+	private async _buildSessionConfig(plan: CopilotSessionLaunchPlan, runtime: ICopilotSessionRuntime): Promise<ResumeSessionConfig> {
 		const plugins = plan.snapshot.plugins;
 		// Synthesize BYOK provider/model config (empty when BYOK is gated off or the
 		// renderer reports no BYOK models), merged into the returned config so both