fix(client-runtime): tolerate transient foreground probe timeouts#5198

Note

Medium Risk Changes live connection monitoring and reconnect timing in client-runtime; behavior is well-covered by supervisor tests but affects when sessions are replaced under load.

Overview Foreground health probes on application-active no longer tear down the session on a single 15s timeout when the host is briefly stalled. The supervisor keeps the existing lease, logs a warning, and only triggers normal reconnect recovery after two consecutive timeouts (FOREGROUND_PROBE_TIMEOUTS_BEFORE_RECONNECT).

A successful probe resets the counter. Definite probe failures and application-active-probe (mobile, 3s timeout) behavior are unchanged.

Tests cover: one timeout stays connected; two timeouts → backoff/release; success between timeouts resets the count.

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Note

Tolerate transient foreground liveness probe timeouts in EnvironmentSupervisor

• During application-active wakeups, a single probe timeout no longer triggers a reconnect; the supervisor only reconnects after 2 consecutive timeouts (FOREGROUND_PROBE_TIMEOUTS_BEFORE_RECONNECT = 2).
• A successful probe resets the timeout counter to 0, so isolated timeouts are always tolerated.
• application-active-probe signals retain the existing fail-fast behavior on timeout.
• Two new tests cover consecutive timeout reconnection and counter reset after a successful probe.

^{Macroscope summarized 3fdbd15.}