fix(ci): cap postgres fixtures and reclaim leftover compose networks

xiaoxin's 20-core npm test opened one Docker network per database file and exhausted default address pools. Limit concurrent fixtures and remove unused jyotisha-postgres networks before the gate.

Co-authored-by: Cursor <cursoragent@cursor.com>

deploy/reclaim-runner-disk.sh

@@ -29,6 +29,30 @@ docker container prune --force --filter until=6h
 docker volume ls --quiet --filter 'name=^jyotisha-postgres-' --filter dangling=true |
   xargs -r docker volume rm
 docker network prune --force --filter until=6h
+
+# Compose networks from crashed or finished fixtures keep occupying Docker's
+# default address pools until they are removed. `network prune --filter until=6h`
+# leaves same-day leftovers, and the next `docker compose up` then fails with
+# "all predefined address pools have been fully subnetted".
+# `docker network rm` refuses networks that still have endpoints, so a
+# concurrent job's live fixture is left alone.
+echo "removing unused jyotisha-postgres compose networks"
+removed_networks=0
+kept_networks=0
+while IFS= read -r network; do
+  if [ -z "$network" ]; then
+    continue
+  fi
+  if docker network rm "$network" >/dev/null 2>&1; then
+    echo "removed unused network $network"
+    removed_networks=$((removed_networks + 1))
+  else
+    echo "kept in-use network $network"
+    kept_networks=$((kept_networks + 1))
+  fi
+done < <(docker network ls --format '{{.Name}}' --filter 'name=jyotisha-postgres-')
+echo "jyotisha-postgres networks: removed=${removed_networks} kept=${kept_networks}"
+
 docker image prune --force
 
 # Exact-SHA release images are immutable in the registry once published, so the