docs(code-runtime-python): name the roster aliases by subset direction, align metering prose

Rename UnionCoversRoster/RosterCoversUnion to UnionSubsetOfRoster/RosterSubsetOfUnion so
the names read in the same direction as their extends clauses, share the python3 -I -B
flags between the two mirror probes, and align the README and Agent Note prose with the
checkDoneValue JSDoc: the escaped-size scan is the metering itself, not deferred work.
Regenerate docs/module-graph.md, which listed code-runtime-python twice.

packages/code-runtime/code-runtime-python/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/code-runtime/code-runtime-python/README.md
-README.md: 606d153eb899925ae274133b3728d317607a17e2
-README.zh.md: f4387d6b20994781b8e64d31da7319badb56aacd
+README.md: e7ca08e3e42d368e1b46f4dd52ae7dc1040e6d76
+README.zh.md: df0488b469daca6f33254ce2233b10e0c7138ed5