mod_auth_digest: cleanup part 5 - #859

* modules/aaa/mod_auth_digest.c (client_entry): Add owner field.
  (DEF_SHMEM_SIZE): Update the entry count for it.
  (nonce_state): Add NONCE_NOT_OWNER.
  (owner_hash): New, a keyed hash of the server name, realm and
  username.
  (client_update_nonce): Record the owner on first use; return
  NONCE_NOT_OWNER for a request from another user, leaving the entry
  alone. Drop const from r.
  (check_and_record_nonce): Challenge NONCE_NOT_OWNER as stale, with a
  new opaque, clearing the quoted one from the record.

* test/modules/aaa/test_015_cross_client.py: New test suite.

* test/modules/aaa/conftest.py: Add a second vhost sharing the realm
  with its own password file, and a tracked section with a domain.

* test/modules/aaa/env.py (AAATestEnv): Write that file.

* test/modules/aaa/htdocs/digest/nccheck-domain/secret.txt: New file.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Co-Authored-By: Claude Mythos 5.1 <noreply@anthropic.com>

* modules/aaa/mod_auth_digest.c (cleanup_tables, log_error_and_cleanup):
  Removed.
  (init_failed): New, replacing them; logs the failure and returns !OK.
  (initialize_tables): Use it.
  (initialize_child): Log a failure and continue with the inherited
  handles.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* modules/aaa/mod_auth_digest.c (check_and_record_nonce): Answer
  NONCE_BAD_COUNT with stale=true like NONCE_STALE.
  (client_update_nonce): Log it at INFO rather than ERR, and without
  the "possible replay attack" wording: an out-of-order nonce-count is
  what a client's concurrent requests look like, and a replay cannot
  answer the new nonce. Alerting on AH01774 at ERR will no longer see
  it.
  (authenticate_digest_user): Expand the comment on the check order.

* test/modules/aaa/test_003_nccheck.py (test_digest_032),
  test/modules/aaa/test_007_replay.py (test_digest_074): Expect stale.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* modules/aaa/mod_auth_digest.c (note_digest_auth_failure): Leave the
  caller's stale flag alone when issuing a new opaque.

* test/modules/aaa/test_001_challenge_response.py (test_digest_016):
  New.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

  unused server argument.
  (note_digest_auth_failure, check_nonce, add_auth_info): Adjust.
  (authenticate_digest_user): Remove the unreachable missing-realm
  checks and the NULL check on new_digest().
  (init_digest_request): Fix the function name in the comment.

No functional change.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

  hostnames with ap_cstr_casecmp().

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* modules/aaa/mod_auth_digest.c (client_note_renewed): Removed.
  (client_generate): Take a renewed flag and count it under the lock
  already held; log the gc summary and any rmm_free failure after
  releasing the lock, so the summary now counts the entry just added.
  (gc): Return the first rmm_free failure as the result, and the count
  through a new argument, instead of logging.
  (note_digest_auth_failure): Adjust.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* modules/aaa/mod_auth_digest.c (check_nonce): The base64 decoder stops
  at the first byte which is not base64, so a nonce of the right length
  could leave part of the decoded time unset. Check the decoded length
  and challenge as stale if it is short, before using the time.

* test/modules/aaa/test_012_truncated_nonce.py
  (test_digest_012_02_time_not_base64): New test.

Co-Authored-By: Claude Mythos 5.1 <noreply@anthropic.com>