Validate implicit if conditions in action.yml files (#317)

## Problem

In workflow YAML files, writing `if: foo == bar` shows an error because `foo` and `bar` are not valid contexts. However, the same invalid expression in an action.yml file showed no error.

## Solution

Add expression validation for implicit `if` conditions in action.yml files, matching the behavior of workflow YAML validation.

## What's new

1. **Pre-if/post-if validation** (node and docker actions)
   - `pre-if: foo == bar` now shows error for unknown context
   - `post-if: unknownFunc()` now shows error for unknown function

2. **Composite step `if` validation** (fix)
   - Errors from `convertToIfCondition` were being lost due to call ordering
   - Now captured correctly by calling conversion before retrieving errors

## Why the refactor?

The diff includes consolidating multiple validation loops into a single `validateAllTokens()` traversal. This matches the pattern used in workflow YAML validation (`additionalValidations`), making the code consistent between the two validation paths.

Author: ericsciple

languageservice/src/validate-action.test.ts

@@ -1011,4 +1011,255 @@ runs:
       expect(diagnostics.some(d => d.code === "format-arg-count-mismatch")).toBe(true);
     });
   });
+
+  describe("if condition context validation", () => {
+    it("warns on unknown context in composite step if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown context in if
+runs:
+  using: composite
+  steps:
+    - if: foo == bar
+      run: echo hi
+      shell: bash
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized named-value"))).toBe(true);
+    });
+
+    it("warns on unknown context in pre-if for node action", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown context in pre-if
+runs:
+  using: node20
+  main: index.js
+  pre: setup.js
+  pre-if: foo == bar
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized named-value"))).toBe(true);
+    });
+
+    it("warns on unknown context in post-if for node action", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown context in post-if
+runs:
+  using: node20
+  main: index.js
+  post: cleanup.js
+  post-if: foo == bar
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized named-value"))).toBe(true);
+    });
+
+    it("warns on unknown context in pre-if for docker action", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown context in pre-if
+runs:
+  using: docker
+  image: Dockerfile
+  pre-entrypoint: /setup.sh
+  pre-if: foo == bar
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized named-value"))).toBe(true);
+    });
+
+    it("warns on unknown context in post-if for docker action", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown context in post-if
+runs:
+  using: docker
+  image: Dockerfile
+  post-entrypoint: /cleanup.sh
+  post-if: foo == bar
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized named-value"))).toBe(true);
+    });
+
+    it("allows valid contexts in composite step if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Valid context in if
+runs:
+  using: composite
+  steps:
+    - if: github.event_name == 'push'
+      run: echo hi
+      shell: bash
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized named-value"))).toBe(false);
+    });
+
+    it("allows valid contexts in pre-if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Valid context in pre-if
+runs:
+  using: node20
+  main: index.js
+  pre: setup.js
+  pre-if: runner.os == 'Linux'
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized named-value"))).toBe(false);
+    });
+
+    it("allows valid contexts in post-if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Valid context in post-if
+runs:
+  using: node20
+  main: index.js
+  post: cleanup.js
+  post-if: runner.os == 'Linux'
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized named-value"))).toBe(false);
+    });
+
+    it("allows hashFiles function in composite step if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: hashFiles in if
+runs:
+  using: composite
+  steps:
+    - if: hashFiles('**/package-lock.json') != ''
+      run: echo hi
+      shell: bash
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized"))).toBe(false);
+    });
+
+    it("allows success, failure, always, cancelled functions in composite step if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Status functions in if
+runs:
+  using: composite
+  steps:
+    - if: success() && !cancelled()
+      run: echo success
+      shell: bash
+    - if: failure()
+      run: echo failure
+      shell: bash
+    - if: always()
+      run: echo always
+      shell: bash
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized"))).toBe(false);
+    });
+
+    it("allows hashFiles function in pre-if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: hashFiles in pre-if
+runs:
+  using: node20
+  main: index.js
+  pre: setup.js
+  pre-if: hashFiles('**/package-lock.json') != ''
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized"))).toBe(false);
+    });
+
+    it("allows status functions in post-if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Status functions in post-if
+runs:
+  using: node20
+  main: index.js
+  post: cleanup.js
+  post-if: always() || failure()
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized"))).toBe(false);
+    });
+
+    it("errors on unknown function in composite step if", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown function in if
+runs:
+  using: composite
+  steps:
+    - if: unknownFunc()
+      run: echo hi
+      shell: bash
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized function"))).toBe(true);
+    });
+
+    it("errors on unknown function in pre-if for node action", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown function in pre-if
+runs:
+  using: node20
+  main: index.js
+  pre: setup.js
+  pre-if: unknownFunc()
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized function"))).toBe(true);
+    });
+
+    it("errors on unknown function in post-if for node action", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown function in post-if
+runs:
+  using: node20
+  main: index.js
+  post: cleanup.js
+  post-if: unknownFunc()
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized function"))).toBe(true);
+    });
+
+    it("errors on unknown function in pre-if for docker action", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown function in pre-if
+runs:
+  using: docker
+  image: Dockerfile
+  pre-entrypoint: /setup.sh
+  pre-if: unknownFunc()
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized function"))).toBe(true);
+    });
+
+    it("errors on unknown function in post-if for docker action", async () => {
+      const doc = createActionDocument(`
+name: My Action
+description: Unknown function in post-if
+runs:
+  using: docker
+  image: Dockerfile
+  post-entrypoint: /cleanup.sh
+  post-if: unknownFunc()
+`);
+      const diagnostics = await validate(doc);
+      expect(diagnostics.some(d => d.message.includes("Unrecognized function"))).toBe(true);
+    });
+  });
 });