Add frame-aware locate for cross-origin iframe steps

Selectors were only resolved against the top document, so steps targeting
the Lucid WooCommerce checkout (rendered in a lucidtrading.com iframe under
the dash.lucidtrading.com app) never matched — e.g. input#coupon_code_field.

Add an optional `frame` on click/type/waitFor naming the <iframe> element.
The extension measures the iframe in the top frame (pageFrameOffset), finds
the element across child frames (pageLocate `relative` mode), and composes
the two into desktop coordinates; the Python side is unchanged since the
result keeps the same shape. Without `frame`, every path behaves as before.

Point the Lucid checkout steps at the frame and harden the coupon selectors
(the exact field id is still unconfirmed against the live iframe).

Extension 0.13.0, runner 0.19.0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

extension/manifest.json

@@ -1,7 +1,7 @@
 {
     "manifest_version": 3,
     "name": "AutoFirmer Capture",
-    "version": "0.12.0",
+    "version": "0.13.0",
 
     "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAxdbOMRR+58a9dHlbIKtlALtS3E4eltBGqfTnUc0lzJuWj5ZA4+5YFSdUnxv5N1ogxwpJUGkUV3MnKJuZnTekCmsNwjCy41a20Xtc7jQLHrIBZkesB6cB+d0l9Vo8M6EC3ZMD8Iv6MdAalU3GZh1Hn9vm24NjJ+xUT1qNIVHEcNUIb9evYobR/XHv+JAp6bOFnaLM+3wpyYKe4efMhsz0F86u9thRNhQnraTqUWfnKNpsHPK2zivaYHrziEEWX7Y3EsMHkf2FRhkUe7IDoxeJM49DBToTo9sAJUkcgLeGCGZLo7H3mcxyn/zERYR+rD3k5xdeBtjoZHXFx2+FanLb9wIDAQAB",
     "update_url": "https://ext.juicerroom.com/updates.xml",