feat: add repository_dispatch event support

- Add new progress MCP server for reporting task status via API
- Support repository_dispatch events with task description and progress endpoint
- Introduce isDispatch flag to unify dispatch event handling
- Make GitHub data optional for dispatch events without issues/PRs
- Update prompt generation with dispatch-specific instructions

Enables triggering Claude via repository_dispatch with:
{
  "event_type": "claude_task",
  "client_payload": {
    "description": "Task description",
    "progress_endpoint": "https://api.example.com/progress"
  }
}

base-action/src/index.ts

@@ -30,7 +30,8 @@ async function run() {
       appendSystemPrompt: process.env.INPUT_APPEND_SYSTEM_PROMPT,
       claudeEnv: process.env.INPUT_CLAUDE_ENV,
       fallbackModel: process.env.INPUT_FALLBACK_MODEL,
-      model: process.env.ANTHROPIC_MODEL,
+      resumeEndpoint: process.env.INPUT_RESUME_ENDPOINT,
+      streamConfig: process.env.INPUT_STREAM_CONFIG,
     });
   } catch (error) {
     core.setFailed(`Action failed with error: ${error}`);