Add missing runner context properties (environment, debug, workspace) (#241)

Fixes #78, #121

Adds three missing properties to the runner context:
- runner.environment: The runner environment (github-hosted or self-hosted)
- runner.debug: Set to '1' when step debug logging is enabled via ACTIONS_STEP_DEBUG
- runner.workspace: The runner-specific working directory path for the job

These are documented official properties that were causing false 'Context access might be invalid' warnings.

languageservice/src/context-providers/default.ts

@@ -83,11 +83,14 @@ function getDefaultContext(name: string, workflowContext: WorkflowContext, mode:
 
     case "runner":
       return objectToDictionary({
-        os: "Linux",
         arch: "X64",
+        debug: "1",
+        environment: "github-hosted",
         name: "GitHub Actions 2",
+        os: "Linux",
+        temp: "/home/runner/work/_temp",
         tool_cache: "/opt/hostedtoolcache",
-        temp: "/home/runner/work/_temp"
+        workspace: "/home/runner/work/repo"
       });
 
     case "secrets":

languageservice/src/context-providers/descriptions.json

@@ -239,7 +239,13 @@
       "description": "The path to the directory containing preinstalled tools for GitHub-hosted runners. For more information, see \"[About GitHub-hosted runners](https://docs.github.com/actions/reference/specifications-for-github-hosted-runners/#supported-software).\""
     },
     "debug": {
-      "description": "This is set only if [debug logging](https://docs.github.com/actions/monitoring-and-troubleshooting-workflows/enabling-debug-logging) is enabled, and always has the value of `1`. It can be useful as an indicator to enable additional debugging or verbose logging in your own job steps."
+      "description": "This is set only if [`ACTIONS_STEP_DEBUG`](https://docs.github.com/actions/monitoring-and-troubleshooting-workflows/enabling-debug-logging) is enabled, and always has the value of `\"1\"`. It can be useful as an indicator to enable additional debugging or verbose logging in your own job steps."
+    },
+    "environment": {
+      "description": "The environment of the runner executing the job. Possible values are `github-hosted` for GitHub-hosted runners, or `self-hosted` for self-hosted runners."
+    },
+    "workspace": {
+      "description": "The runner-specific working directory path for the job."
     }
   },
   "strategy": {