feat: add --download-path option (#536)

* feat: add --download-path option

Adds a `--download-path` flag (and `AGENT_BROWSER_DOWNLOAD_PATH` env / `downloadPath` config key) to set a default download directory for browser downloads.

Without this, Playwright stores downloads in a temp directory that is deleted when the browser closes. The new option passes through to Playwright's `downloadsPath` on `launch()` and `launchPersistentContext()`.

Fixes #507

* improvements

* fixes

* fixes

src/protocol.ts

@@ -50,6 +50,7 @@ const launchSchema = baseCommandSchema.extend({
   ignoreHTTPSErrors: z.boolean().optional(),
   allowFileAccess: z.boolean().optional(),
   colorScheme: z.enum(['light', 'dark', 'no-preference']).optional(),
+  downloadPath: z.string().optional(),
   profile: z.string().optional(),
   storageState: z.string().optional(),
 });