* fix: snapshot --selector scopes to the matched element subtree
The native Rust daemon accepted the --selector flag but never used it —
the full accessibility tree was always returned regardless of the
selector. This restores the 0.19.0 behaviour where snapshot --selector
returns only the subtree rooted at the matched CSS selector.
The implementation resolves the selector via Runtime.evaluate, fetches
the full DOM subtree with DOM.describeNode(depth: -1) to collect all
descendant backendNodeIds, then filters the AX tree to render only the
nodes whose backendDOMNodeId falls within that set. This correctly
handles elements like <body> that don't map to a direct AX node.
Also fixes handle_snapshot reading "depth" instead of "maxDepth" from
the command JSON, which caused --depth to be silently ignored.
Fixes#822
* style: run cargo fmt on snapshot.rs
---------
Co-authored-by: ctate <366502+ctate@users.noreply.github.com>
