feat(docs): simplify custom GitHub App creation with manifest support (#620)

* feat(docs): simplify custom GitHub App creation with manifest support

- Add github-app-manifest.json with pre-configured permissions
- Create interactive HTML tool for one-click app creation
- Update setup.md documentation with manifest-based instructions
- Maintain existing manual setup as alternative option

This significantly improves the developer experience by eliminating
manual permission configuration and reducing setup time from multiple
steps to a single click.

Fixes #619

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

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Kris Coleman <kriscodeman@gmail.com>

* feat: create-app ux improvements

Signed-off-by: Kris Coleman <kriscodeman@gmail.com>

---------

Signed-off-by: Kris Coleman <kriscodeman@gmail.com>
Co-authored-by: Claude <noreply@anthropic.com>

docs/setup.md

@@ -20,7 +20,48 @@ If you prefer not to install the official Claude app, you can create your own Gi
 - Organization policies prevent installing third-party apps
 - You're using AWS Bedrock or Google Vertex AI
 
-**Steps to create and use a custom GitHub App:**
+### Option 1: Quick Setup with App Manifest (Recommended)
+
+The fastest way to create a custom GitHub App is using our pre-configured manifest. This ensures all permissions are correctly set up with a single click.
+
+**Steps:**
+
+1. **Create the app:**
+
+   **🚀 [Download the Quick Setup Tool](./create-app.html)** (Right-click → "Save Link As" or "Download Linked File")
+
+   After downloading, open `create-app.html` in your web browser:
+
+   - **For Personal Accounts:** Click the "Create App for Personal Account" button
+   - **For Organizations:** Enter your organization name and click "Create App for Organization"
+
+   The tool will automatically configure all required permissions and submit the manifest.
+
+   Alternatively, you can use the manifest file directly:
+
+   - Use the [`github-app-manifest.json`](../github-app-manifest.json) file from this repository
+   - Visit https://github.com/settings/apps/new (for personal) or your organization's app settings
+   - Look for the "Create from manifest" option and paste the JSON content
+
+2. **Complete the creation flow:**
+
+   - GitHub will show you a preview of the app configuration
+   - Confirm the app name (you can customize it)
+   - Click "Create GitHub App"
+   - The app will be created with all required permissions automatically configured
+
+3. **Generate and download a private key:**
+
+   - After creating the app, you'll be redirected to the app settings
+   - Scroll down to "Private keys"
+   - Click "Generate a private key"
+   - Download the `.pem` file (keep this secure!)
+
+4. **Continue with installation** - Skip to step 3 in the manual setup below to install the app and configure your workflow.
+
+### Option 2: Manual Setup
+
+If you prefer to configure the app manually or need custom permissions:
 
 1. **Create a new GitHub App:**