feat(portal): tile headline is Leq, not Lp; note live-map for M2

Lp (instantaneous) twitches every reading and makes a poor at-a-glance headline;
Leq (energy-average) is the stable, standard sound-monitoring/compliance metric.
Overview tiles now lead with Leq. Design doc: live project map (status-colored
pins + current-reading popups) recorded as an M2 item; headline-metric rationale
noted.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/CLIENT_PORTAL.md

@@ -118,10 +118,19 @@ live data, all from cache.
       page or a script for now).
 
 ### M2 — Dashboard + alerts
-- Richer client dashboard (multi-location at-a-glance, map, status rollup).
+- Richer client dashboard (multi-location at-a-glance, status rollup).
+- **Live project map** — upgrade the overview's basic location pins into a real
+  project map: pins colored by measuring/level, popups showing each location's
+  current reading, centered/zoomed to the project. (M1 ships the plain pin map;
+  this makes it a live status map.)
 - Surface each location's **threshold-alert status** (read-only) + an event/inbox
   view. Leans on the SLMM alert engine + dispatch.
 
+### Notes carried from M1
+- Tile headline metric is **Leq** (energy-average, the sound-monitoring compliance
+  metric) — chosen over the twitchy instantaneous Lp. If clients ever want a
+  different headline (e.g. Lmax for peaks), make it a per-deployment setting.
+
 ### M3 — Reports
 - Client-facing list + download of the daily baseline-comparison reports.
 - Depends on the FTP report pipeline (`feat/ftp-report-pipeline`) landing and