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/mockContext.ts

@@ -1,6 +1,7 @@
 import type {
   ParsedGitHubContext,
   AutomationContext,
+  RepositoryDispatchEvent,
 } from "../src/github/context";
 import type {
   IssuesEvent,
@@ -81,6 +82,33 @@ export const createMockAutomationContext = (
   return { ...baseContext, ...overrides, inputs: mergedInputs };
 };
 
+export const mockRepositoryDispatchContext: AutomationContext = {
+  runId: "1234567890",
+  eventName: "repository_dispatch",
+  eventAction: undefined,
+  repository: defaultRepository,
+  actor: "automation-user",
+  payload: {
+    action: "trigger-analysis",
+    client_payload: {
+      source: "issue-detective",
+      issue_number: 42,
+      repository_name: "test-owner/test-repo",
+      analysis_type: "bug-report",
+    },
+    repository: {
+      name: "test-repo",
+      owner: {
+        login: "test-owner",
+      },
+    },
+    sender: {
+      login: "automation-user",
+    },
+  } as RepositoryDispatchEvent,
+  inputs: defaultInputs,
+};
+
 export const mockIssueOpenedContext: ParsedGitHubContext = {
   runId: "1234567890",
   eventName: "issues",