Test plan ledger

Tracks behavior verified manually (one-shot) but not yet covered by a committed
test. Per AGENTS.md, an entry here is a debt:
it names the test that must replace the manual check. An empty ledger is the
goal - a growing one is a smell.

Resolved:

• carve exit-code mapping (missing/unknown subcommand → 2, failed refresh → 1)
  is covered by //carve/e2e:end_to_end_test.
• carve refresh --aquery_proto=FILE producing a CDB is covered by the same
  end-to-end test.
• carve refresh --targets=… (in-process bazel aquery plus the
  bazel info execution_root directory default) is covered hermetically by
  //carve/e2e:end_to_end_test using a fake bazel stub.