Flasksimpleauth

- improve resilience of post request handler, again

- improve `current_user` resilience.

- add `FSA_JSON_ALLSTR` to cast values with `str` when in doubt.

- require _Flask 3_ (September 2023) to use JSON provider infrastructure and _CacheToolsUtils 10.0_.
- add `FSA_JSON_CONVERTER` directive to manage per-type JSON serialization
- add `add_json_converter` per-type hook registration.

- unsuccessful attempt at adding _Python 3.14_ to CI.
- improve dev automations, including parallelizing tests.
- improve tutorial.
- add experimental `FSA_CACHED_OPTS` directive.

- add JsonData section to tutorial.
- password manager refactoring
- add **experimental** support for _LDAP_ authentication.