`_finite_positive_config_float` and `_config_int` were the same shape with the warn call
pasted six times and asymmetric sign checks. Collapse both onto `_liveness_knob(key, default,
cast)`: usable iff finite, >= 0 and exact for the cast; else warn and return 0; explicit 0
stays silent.
Two int-path holes closed on the way: `websocket_liveness_failure_threshold: .inf` raised
OverflowError inside `DiscordAdapter.__init__`, and `0.5` truncated to 0 and disabled the
probe silently — the bug class this PR exists to remove. `2.0` / `"2"` still resolve to 2.
5dcd4844bd