Add missing validation for action.yml (parity with workflow files) (#311)

* Add missing validation for action.yml (parity with workflow files)

- Add uses format validation for composite action steps
  - Validates owner/repo@ref format
  - Supports docker:// and ./ local references
  - Warns about shortened SHA refs (security concern)
  - Detects reusable workflow references in wrong context

- Add if literal text detection for composite action steps
  - Detects literal text outside ${{ }} that makes conditions always truthy
  - Works for both plain string and mixed expression formats
  - Uses shared hasFormatWithLiteralText() utility

- Add pre-if/post-if validation for node and docker actions
  - Errors on explicit ${{ }} syntax (runner only supports implicit expressions)
  - Literal text detection for implicit expressions
  - New runs-if schema type with proper context (runner, github, job, env, inputs, status functions)
  - Validates only in strict schema used by language services

- Add format() function validation for all expressions
  - Validates format string syntax in all expression contexts
  - Checks argument count matches placeholders

- Fix env and matrix context providers to return complete=false
  - Prevents false positive 'unknown context' errors
  - Matches behavior of other dynamic contexts (secrets, vars, etc.)

- Refactor validation utilities into utils/validate-uses.ts and utils/validate-if.ts
  - Shared between workflow and action validation
  - Consistent error messages and codes

* Add strategy and matrix contexts to runs-if definition

Based on runner source code analysis (actions/runner):
- ExecutionContext.InitializeJob() populates ExpressionValues from message.ContextData
- strategy and matrix are part of message.ContextData, available before any steps run
- StepsRunner evaluates all steps (pre, main, post) using the same code path

Did NOT add:
- steps: empty at pre-if time (no steps completed yet)
- hashFiles: workspace files don't exist at pre-step time

workflow-parser/src/action-v1.0.json

@@ -137,6 +137,23 @@
       ],
       "string": {}
     },
+    "runs-if": {
+      "description": "Condition to control when this action's pre or post script runs.",
+      "context": [
+        "runner",
+        "github",
+        "job",
+        "strategy",
+        "matrix",
+        "env",
+        "inputs",
+        "always(0,0)",
+        "success(0,0)",
+        "failure(0,0)",
+        "cancelled(0,0)"
+      ],
+      "string": {}
+    },
     "runs": {
       "one-of": [
         "container-runs",
@@ -242,7 +259,7 @@
             "description": "Allows you to run a script before the entrypoint action begins.\n\n[Documentation](https://docs.github.com/actions/creating-actions/metadata-syntax-for-github-actions#runspre-entrypoint)"
           },
           "pre-if": {
-            "type": "non-empty-string",
+            "type": "runs-if",
             "description": "Allows you to define conditions for the pre: action execution. The pre: action will only run if the conditions in pre-if are met. If not set, then pre-if defaults to always().\n\n[Documentation](https://docs.github.com/actions/creating-actions/metadata-syntax-for-github-actions#runspre-if)"
           },
           "post-entrypoint": {
@@ -250,7 +267,7 @@
             "description": "Allows you to run a cleanup script once the runs.entrypoint action has completed.\n\n[Documentation](https://docs.github.com/actions/creating-actions/metadata-syntax-for-github-actions#runspost-entrypoint)"
           },
           "post-if": {
-            "type": "non-empty-string",
+            "type": "runs-if",
             "description": "Allows you to define conditions for the post: action execution. The post: action will only run if the conditions in post-if are met. If not set, then post-if defaults to always().\n\n[Documentation](https://docs.github.com/actions/creating-actions/metadata-syntax-for-github-actions#runspost-if)"
           }
         }
@@ -275,7 +292,7 @@
             "description": "Allows you to run a script at the start of a job, before the main: action begins. You can use pre: to run prerequisite setup scripts.\n\n[Documentation](https://docs.github.com/actions/creating-actions/metadata-syntax-for-github-actions#runspre)"
           },
           "pre-if": {
-            "type": "non-empty-string",
+            "type": "runs-if",
             "description": "Allows you to define conditions for the pre: action execution. The pre: action will only run if the conditions in pre-if are met. If not set, then pre-if defaults to always().\n\n[Documentation](https://docs.github.com/actions/creating-actions/metadata-syntax-for-github-actions#runspre-if)"
           },
           "post": {
@@ -283,7 +300,7 @@
             "description": "Allows you to run a script at the end of a job, once the main: action has completed. You can use post: to run cleanup scripts.\n\n[Documentation](https://docs.github.com/actions/creating-actions/metadata-syntax-for-github-actions#runspost)"
           },
           "post-if": {
-            "type": "non-empty-string",
+            "type": "runs-if",
             "description": "Allows you to define conditions for the post: action execution. The post: action will only run if the conditions in post-if are met. If not set, then post-if defaults to always().\n\n[Documentation](https://docs.github.com/actions/creating-actions/metadata-syntax-for-github-actions#runspost-if)"
           }
         }