feat(natives): enabled per-language rewrite rules for mixed-language paths

- Remove uniform language inference requirement, allowing mixed-language paths to rewrite each file in its own language.
- Update `ast_edit_blocking` in `crates/pi-natives/src/ast.rs` to compile rewrite rules per language and skip unsupported languages gracefully.
- Update `ast-edit.md` prompt documentation to reflect mixed-language path support.
- Add test coverage verifying mixed-language tree rewrites.

crates/pi-shell/src/shell.rs

@@ -3029,7 +3029,8 @@ mod tests {
 		session
 			.shell
 			.run_string(
-				"export PI_EXEC_ENV=zed; find . -name keep.log -exec sh -c 'echo \"$PI_EXEC_ENV $1\"' sh {} ';' > cap.txt",
+				"export PI_EXEC_ENV=zed; find . -name keep.log -exec sh -c 'echo \"$PI_EXEC_ENV $1\"' \
+				 sh {} ';' > cap.txt",
 				&si,
 				&params,
 			)