Add language service support for action.yml files (#275)

- Add validation, completion, hover, and document links for action.yml files
- Implement document type detection to route action.yml to action-specific handlers
- Add expression context for composite actions (inputs, steps, github, runner, etc.)
- Add schema validation for required fields, branding, and composite step requirements
- Support JavaScript (node20/node24), Docker, and composite action types
- Validate action references in composite action uses steps
- Add JSDoc comments to parser and template functions
- Refactor hover to use hoverToken consistently
- Fix lint errors and add return type annotations

languageserver/src/context-providers/steps.test.ts

@@ -84,13 +84,17 @@ it("outputs is an incomplete dictionary to allow dynamic outputs", async () => {
 
   // Get the step context
   const stepContext = stepsContext?.get("cache-primes");
-  expect(stepContext).toBeDefined();
-  expect(isDescriptionDictionary(stepContext!)).toBe(true);
+  if (!stepContext) {
+    throw new Error("Expected stepContext to be defined");
+  }
+  expect(isDescriptionDictionary(stepContext)).toBe(true);
 
   // Get the outputs - should be a dictionary, not null
   const outputs = (stepContext as DescriptionDictionary).get("outputs");
-  expect(outputs).toBeDefined();
-  expect(isDescriptionDictionary(outputs!)).toBe(true);
+  if (!outputs) {
+    throw new Error("Expected outputs to be defined");
+  }
+  expect(isDescriptionDictionary(outputs)).toBe(true);
 
   // Outputs should be marked incomplete to allow dynamic outputs
   const outputsDict = outputs as DescriptionDictionary;