perf(martin+postgres): connection pool limit + compound indexes + minzoom alignment

- Martin: pool_size=8 (prevents overwhelming PostgreSQL with concurrent queries)
- Martin: gis_terenuri minzoom 10→14, gis_cladiri minzoom 12→15
  (PMTiles serves z0-z14, no point in Martin generating those)
- PostGIS: add compound index layerId+geom for Martin view queries
- PostGIS: add B-tree index on layerId for LIKE filtering in views

Fixes 90% CPU on PostgreSQL during cold tile loads at detail zoom levels.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

prisma/postgis-setup.sql

@@ -59,6 +59,14 @@ WHERE geometry IS NOT NULL AND geom IS NULL;
 CREATE INDEX IF NOT EXISTS gis_feature_geom_idx
   ON "GisFeature" USING GIST (geom);
 
+-- Compound index: layerId + spatial — Martin queries filter by layer via views
+CREATE INDEX IF NOT EXISTS gis_feature_layer_geom_idx
+  ON "GisFeature" ("layerId", geom) WHERE geom IS NOT NULL;
+
+-- B-tree index on layerId for view filtering (LIKE 'TERENURI%', 'CLADIRI%')
+CREATE INDEX IF NOT EXISTS gis_feature_layer_id_idx
+  ON "GisFeature" ("layerId");
+
 -- =============================================================================
 -- 7. QGIS-friendly views
 --    - Clean snake_case column names