Add entrypoint and command keys for service containers (#343)

Introduce service-container-mapping schema definition with entrypoint
and command properties, gated behind allowServiceContainerCommand
feature flag. Job containers remain unaffected.

expressions/src/features.test.ts

@@ -55,7 +55,8 @@ describe("FeatureFlags", () => {
         "missingInputsQuickfix",
         "blockScalarChompingWarning",
         "allowCaseFunction",
-        "allowCopilotRequestsPermission"
+        "allowCopilotRequestsPermission",
+        "allowServiceContainerCommand"
       ]);
     });
   });

expressions/src/features.ts

@@ -40,6 +40,12 @@ export interface ExperimentalFeatures {
    * @default false
    */
   allowCopilotRequestsPermission?: boolean;
+
+  /**
+   * Enable `entrypoint` and `command` keys in service containers (`jobs.<job_id>.services.*`).
+   * @default false
+   */
+  allowServiceContainerCommand?: boolean;
 }
 
 /**
@@ -55,7 +61,8 @@ const allFeatureKeys: ExperimentalFeatureKey[] = [
   "missingInputsQuickfix",
   "blockScalarChompingWarning",
   "allowCaseFunction",
-  "allowCopilotRequestsPermission"
+  "allowCopilotRequestsPermission",
+  "allowServiceContainerCommand"
 ];
 
 export class FeatureFlags {