feat: add repository_dispatch event support (#546)

* feat: add repository_dispatch event support

Add support for repository_dispatch events in GitHub context parsing system. This enables the action to handle custom API-triggered events properly.

Changes:
- Add RepositoryDispatchEvent type definition
- Include repository_dispatch in automation event names
- Update context parsing to handle repository_dispatch events
- Update documentation to reflect repository_dispatch availability

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* style: format code with prettier

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* test: add comprehensive repository_dispatch event test coverage

- Add mockRepositoryDispatchContext with realistic payload structure
- Add repository_dispatch mode detection tests in registry.test.ts
- Add repository_dispatch trigger tests in agent.test.ts
- Ensure repository_dispatch events are properly handled as automation events
- Verify agent mode trigger behavior with and without prompts
- All 394 tests passing with new coverage

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* style: format test files with prettier

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

test/modes/agent.test.ts

@@ -76,6 +76,11 @@ describe("Agent Mode", () => {
     });
     expect(agentMode.shouldTrigger(scheduleContext)).toBe(false);
 
+    const repositoryDispatchContext = createMockAutomationContext({
+      eventName: "repository_dispatch",
+    });
+    expect(agentMode.shouldTrigger(repositoryDispatchContext)).toBe(false);
+
     // Should NOT trigger for entity events without prompt
     const entityEvents = [
       "issue_comment",
@@ -92,6 +97,7 @@ describe("Agent Mode", () => {
     // Should trigger for ANY event when prompt is provided
     const allEvents = [
       "workflow_dispatch",
+      "repository_dispatch",
       "schedule",
       "issue_comment",
       "pull_request",
@@ -101,7 +107,9 @@ describe("Agent Mode", () => {
 
     allEvents.forEach((eventName) => {
       const contextWithPrompt =
-        eventName === "workflow_dispatch" || eventName === "schedule"
+        eventName === "workflow_dispatch" ||
+        eventName === "repository_dispatch" ||
+        eventName === "schedule"
           ? createMockAutomationContext({
               eventName,
               inputs: { prompt: "Do something" },