Real-socket tests for the timer family in E37 §10 — these replace
the "the timer fires somewhere" implicit assumption with
end-to-end observations on a loopback pair:
T3: send_request that gets no reply emits S9F9 with the original
MHEAD echoed in the body and surfaces Timeout to the caller.
T6: active mode whose Select.req goes unanswered self-closes
with a "T6 timeout on Select" reason.
T7: passive mode that never receives Select.req self-closes
with a "T7 not-selected timeout" reason.
T8: peer sends only the 4-byte length prefix; T8 expires mid-read
and closes with "T8 intercharacter timeout".
Plus S9F11 emission for an over-length frame (length prefix of
1 GiB+1) — body's <B 10> echoes the offending bytes verbatim.
Per-test timer profiles (only the timer under test is short, the
rest are 5s) so the FSM isn't racing against unrelated timers.
Closes#5 in the test-gap backlog.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
