test: implement fixed Linux late-slope diagnostic mode

scripts/validation/opcua-lifecycle-memory/LATE_SLOPE.md

@@ -47,6 +47,10 @@ have at least 10 samples, first sample no later than 60s after its start, last s
 no earlier than 60s before its end, observed span at least 480s, and no internal gap
 above 60s. Apply the same 60s maximum gap over the entire 1800–7200s reporting range.
 Missing coverage is incomplete evidence; it must not become a favorable slope.
+If fewer than 385 cycles and 96 restarts complete by 1800s, report the elapsed
+slopes descriptively but withhold attribution to the phase after the previously
+observed restart milestone. Reaching that count still does not prove factory
+saturation in this run; no EventPipe observer is attached.
 
 For each window report sample count, first/last/min/max/median RSS and retained
 managed bytes, FD range, GC committed range, JIT/timer/thread ranges and elapsed
@@ -74,6 +78,9 @@ alongside any later cleanup failure; neither error may erase the other.
 
 Before execution, implement and review the proposed setup/last-cycle/cleanup and
 outer deadlines in the actual harness and launcher; no extension or retry-to-green.
+Cycle cancellation is cooperative. If a call ignores its token and does not
+return within the bound, the diagnostic is incomplete; the outer deadline reaps
+the task-owned container. Never infer a completed bounded cycle from silence.
 Require negative controls proving a latched first failure cannot disappear,
 wrong duration/mode is rejected, no ordinary acceptance receipt can be emitted,
 and malformed/missing sample windows fail the summarizer. Review actual source,