Address CodeRabbit review on #1320:
- _env_float now requires math.isfinite(value): "inf"/"Infinity"/"1e309"/
"nan" are positive-or-parseable but would produce unusable socket/timeout
behaviour, so they now fall back to the default like other invalid input.
- test_config_default_values clears the two env vars first so ambient env
can't mask the defaults.
- Added coverage for valid overrides and for invalid/zero/negative/
non-finite values falling back to defaults.
Andriy Mykhaylyshyn
7997788edb