Stabilize Docker startup and runtime proxy

Reduce cold-start stalls by raising the default backend memory limit, bounding heavy feed concurrency, preserving non-empty startup caches, and refreshing working news feeds. Fix the Next API proxy for Docker control-plane writes by stripping unsupported hop/body headers and forwarding small request bodies safely. Keep the dashboard dynamic so production users do not get stuck on a cached startup shell.

.env.example

@@ -58,6 +58,15 @@ ADMIN_KEY=
 # FAST_STARTUP_CACHE_MAX_AGE_S=21600
 # INTEL_STARTUP_CACHE_MAX_AGE_S=21600
 
+# Docker resource tuning. The backend synthesizes large geospatial feeds; keep
+# this at 4G or higher on hosts that run AIS, OpenSky, CCTV, satellites, and
+# threat feeds together. Lower caps can cause Docker OOM restarts and empty
+# slow layers such as news, UAP sightings, military bases, and wastewater.
+# BACKEND_MEMORY_LIMIT=4G
+# SHADOWBROKER_FETCH_WORKERS=8
+# SHADOWBROKER_SLOW_FETCH_CONCURRENCY=4
+# SHADOWBROKER_STARTUP_HEAVY_CONCURRENCY=2
+
 # Google Earth Engine for VIIRS night lights change detection (optional).
 # pip install earthengine-api
 # GEE_SERVICE_ACCOUNT_KEY=