feat: support remote CDP WebSocket URLs in --cdp flag (#99)

Previously, the --cdp flag only accepted a port number and connected via
http://localhost:{port}. This made it impossible to connect to remote
browser services like Kernel, Browserless, etc. that provide WebSocket URLs.

The --cdp flag now accepts either:
- A port number (e.g., 9222) for local connections
- A full WebSocket URL (e.g., wss://...) for remote browser services

Changes:
- Added cdpUrl field to LaunchCommand type
- Updated protocol validation to accept URL format with scheme validation
- Modified connectViaCDP to detect and handle both formats
- Handle numeric strings for JSON serialization edge cases
- Updated CLI to send cdpUrl or cdpPort based on input format
- Updated README with examples for remote connections

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

src/protocol.ts

@@ -19,6 +19,18 @@ const launchSchema = baseCommandSchema.extend({
     .optional(),
   browser: z.enum(['chromium', 'firefox', 'webkit']).optional(),
   cdpPort: z.number().positive().optional(),
+  cdpUrl: z
+    .string()
+    .url()
+    .refine(
+      (url) =>
+        url.startsWith('ws://') ||
+        url.startsWith('wss://') ||
+        url.startsWith('http://') ||
+        url.startsWith('https://'),
+      { message: 'CDP URL must start with ws://, wss://, http://, or https://' }
+    )
+    .optional(),
   executablePath: z.string().optional(),
   extensions: z.array(z.string()).optional(),
   headers: z.record(z.string()).optional(),