ci(ai-validation): collapse split-backtick comment span (Copilot)

Copilot finding on #1974/#1975: the inline backtick code span
`[ -s diff-md.patch ] && [ ! -d .reference-db/extracted ]` was split
across two YAML comment lines, which renders poorly in Markdown
viewers (the backtick crosses the line boundary).

Reworded to put the relevant filesystem-presence check (`-d
.reference-db/extracted`) on a single line and drop the redundant
`-s diff-md.patch` half — the latter is the job-level gate
condition, not part of the fail-closed gate logic, so omitting it
from this rationale comment removes the wrap-required spread without
losing meaning. The `-d` check on its own is what defines "the gate
is a presence check, not a schema check".

Mirrored byte-identically across rolling/circinus/sagitta.

0 files changed, 0 insertions, 0 deletions