fix: include AGENTS.md as repo root marker for integration tests (#9010)

As explained in `codex-rs/core/BUILD.bazel`, including the repo's own
`AGENTS.md` is a hack to get some tests passing. We should fix this
properly, but I wanted to put stake in the ground ASAP to get `just
bazel-remote-test` working and then add a job to `bazel.yml` to ensure
it keeps working.

codex-rs/core/BUILD.bazel

@@ -20,6 +20,15 @@ codex_rust_crate(
         "//codex-rs/apply-patch:apply_patch_tool_instructions.md",
         "prompt.md",
     ],
+    # This is a bit of a hack, but empirically, some of our integration tests
+    # are relying on the presence of this file as a repo root marker. When
+    # running tests locally, this "just works," but in remote execution,
+    # the working directory is different and so the file is not found unless it
+    # is explicitly added as test data.
+    #
+    # TODO(aibrahim): Update the tests so that `just bazel-remote-test` succeeds
+    # without this workaround.
+    test_data_extra = ["//:AGENTS.md"],
     integration_deps_extra = ["//codex-rs/core/tests/common:common"],
     test_tags = ["no-sandbox"],
     extra_binaries = [