feat(linkedin-studio): RE-R3d — temporal overlay (first-mover + saturation) [skip-docs]

R3 slice (b): the rest of hull #3. The morning brief now reads the temporal axis
the R3b seen-log records but the ranking ignored. Two DERIVED signals, computed at
brief time from already-persisted fields (publishedAt/capturedAt -> ageDays,
surfacedCount), never stored:

- first-mover: recent (ageDays <= --first-mover-days, default 2) AND never surfaced
  on a prior day -> ranked up, badge "first ute". Future-dated (ageDays<0) excluded.
- saturation: surfaced on >= --saturation-at (default 3) prior days -> ranked down,
  badge "mettet (Nx)". Self-surfacing (our seen-log), not market coverage.
- warming (1..at-1) keeps the R3b "sett Nx" badge but only at >=2 (contract intact);
  neutral carries no badge.

SB1 derived (no schema bump: SCHEMA_VERSION 4 / BRIEF_SCHEMA_VERSION 1 untouched).
SB2 the R3a relevance composite stays the PRIMARY sort key; the temporal rank is a
new cmp key after pillar-overlap, before effectiveDate -> re-orders only WITHIN a
(composite, overlap) tier. temporalSignal is pure (saturationAt clamped >=1).

Prior-day surfacings exclude today (via lastSurfacedAt), so a same-day re-render is
byte-identical (caught by the R3c run-daily SC7 regression; fixes a latent R3b
prior-day imprecision too). brief CLI gains --first-mover-days / --saturation-at;
schedule untouched (nightly uses defaults).

Wiring: trend-spotter.md (prose), trend-scoring-modes.md (one-line consumer note),
README (## Temporal overlay), gate Section 16m (+6 unconditional -> ASSERT floor
111->117), TRENDS_TESTS_FLOOR 192->216. Counts 29/19/27 unchanged. Zero new files.

Gate: Passed 132 / Failed 0; trends 216/216; hook suite 139/139 untouched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011vmzxpsFpc8q19LaogAWLD

references/trend-scoring-modes.md

@@ -98,3 +98,8 @@ The same priority bands apply to both modes (the composite is on the same 0–10
   instead of inlining a matrix (wired in research-engine slice 2b).
 - Any future research-engine pass that scores candidates before writing them to the trend
   store (`scripts/trends/`).
+
+**Note (RE-R3d):** the morning brief applies a *brief-time* **temporal overlay** (first-mover /
+saturation, derived from the publish/capture dates + the seen-log) as a **within-composite-tier**
+ranking refinement. It is a separate layer from this file — it does **not** change the capture-time
+dimension weights, bands, or composite formula above.