fix(code-runtime-python): bind the _done_with_value entry name and correct the residual documentation

Addresses the review's registration-text accuracy findings:
- _run binds _done_with_value into a local (done_with_value_bound) before the
  program runs, closing the __main__._done_with_value = boom success-rewrite
  vector; a regression test rebinds it and returns a legitimate value, asserting
  the success survives.
- README (en + zh): the CPU-recheck bullet now states the recheck runs
  unconditionally after the program returns (a pre-return overrun dies there as
  a timeout) and the false-success window is only a trap-SIGXCPU program that
  passes the recheck and overruns during the settlement flush/encode; the
  encoder-deps residual rationale is replaced with the actual one (bash-equivalent
  trust, verdict still delivered via the send_done fallback frame) and names the
  now-bound entry; the t.join() deadlock bullet fixes the subject/object (the
  main coroutine joins the worker, blocking the pump's main event loop).
- The portable-identifier-seam architecture note no longer claims the Python
  backend does not exist.
- Settlement note (en + zh) registers the entry-name binding and the new test.
- All pairings re-recorded; corpus-wide verify-translation-pairing passes 1004.

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: f976b050992863cc8586b5415d9c36cfe193229e
-README.zh.md: 608ac28ecab35f90d9a9d6582e15a24fa4e78c10
+README.md: 3522c7726460b10f0366c56566336465a76491c5
+README.zh.md: 95984cf1ae3677aff4a5c4565bed87a57701d086