Deja Vu v0.3.1

Deja Vu v0.3.1 is a recall-quality patch for the cue-first protocol release.

Highlights

deja-vu-lint-memory now warns when impression cues are too sparse, too large, duplicated, too generic, or repeated across records.
Default engine summaries now preserve gist cues as decision, rationale, and trigger fields when those labels are available.
Default engine chunking now respects Markdown headings and paragraph boundaries before using hard character splits.
The patch keeps the v0.3 protocol surface unchanged while making low-token recall routes cleaner and less noisy.