fix(lsp): mark late-auxiliary coverage at notify time, not ceiling expiry (refs #3482) - #3486

…piry (refs apmantza#3482)

The turn-end drain uses markPendingAuxiliaryCoverage's timestamp as the
freshness baseline for a collect-later auxiliary pair, checking a file's
mtime against it to decide whether a later scan result still describes
the current revision. The mark was stamped with Date.now() at the point
where the aux-grace ceiling wait gives up, which is up to auxGraceMs
(2000ms by default) after the touch's own notify actually went out. An
edit landing inside that window gets an mtime earlier than the mark, so
the drain reads the file as unmodified since the mark and delivers the
scanner's findings for the file's prior revision as if they were fresh.

Pass startedAt (stamped at touchFile's own entry, before any spawn or
wait work) instead. It's the same anchor apmantza#2324's napi-fallback staleness
check already uses two lines above for an identical concern, and it is
the earliest instant this touch could possibly predate, which is what
this baseline needs to be conservative in the right direction.

This covers the EditDuringGrace scenario from apmantza#3482. The issue's other
scenario, ReTouchRemark, needs two more parts per the issue's own TLA+
model (binding the mark to the scanner's outstanding-publish count, and
preserving the baseline across a stale re-arm) that touch shared refresh
logic in runtime-turn.ts and have an edge case the model itself flags as
uncovered (a scanner that publishes more than once per scan). That's a
maintainer design call, not a mechanical fix, so it's left as a
follow-up rather than bundled in here.