010: fix verification - compare pg_settings raw values, not SHOW output

SHOW() pretty-renders units (60s -> '1min'), which broke the post-up
check after a successful apply. Compare pg_settings.setting (base-unit
raw values) instead - rendering-proof.

migrations/010-tune-postgres.sh

@@ -23,14 +23,19 @@ PGBIN=/etc/postgresql/18/main
 CONF=$PGBIN/conf.d/010-tune-postgres.conf
 CLUSTER=$(pg_lsclusters --no-header | awk 'NR==1{print $1"/"$2}')
 
-# desired state as "guc value" pairs; SHOW renders exactly these strings
+# desired state as "guc raw_value" pairs, compared against pg_settings.setting
+# (each GUC's base unit). Immune to SHOW()'s pretty unit rendering -
+# SHOW renders 60000ms as '1min', 2097152kB as '2GB', etc.
+#   max_connections          -      effective_cache_size 8kB
+#   work_mem                 kB     *_timeout          ms
+#   temp_file_limit          kB
 WANT=(
   'max_connections 30'
-  'effective_cache_size 768MB'
-  'work_mem 4MB'
-  'statement_timeout 30s'
-  'idle_in_transaction_session_timeout 60s'
-  'temp_file_limit 2GB'
+  'effective_cache_size 98304'                # 768MB
+  'work_mem 4096'                             # 4MB
+  'statement_timeout 30000'                   # 30s
+  'idle_in_transaction_session_timeout 60000' # 60s
+  'temp_file_limit 2097152'                   # 2GB
 )
 
 pg() { runuser -u postgres -- psql -d postgres -v ON_ERROR_STOP=1 -tAc "$1"; }
@@ -63,7 +68,7 @@ case "${1:-}" in
     fi
     for kv in "${WANT[@]}"; do
       read -r guc want <<<"$kv"
-      got=$(pg "SHOW $guc")
+      got=$(pg "SELECT setting FROM pg_settings WHERE name='$guc'")
       [[ $got == "$want" ]] || { echo "FATAL: $guc is '$got', expected '$want'" >&2; exit 1; }
     done
     echo "    ${#WANT[@]} memory/stability settings active"
@@ -81,7 +86,7 @@ case "${1:-}" in
     bad=()
     for kv in "${WANT[@]}"; do
       read -r guc want <<<"$kv"
-      got=$(q "SHOW $guc" 2>/dev/null)
+      got=$(q "SELECT setting FROM pg_settings WHERE name='$guc'" 2>/dev/null)
       [[ $got == "$want" ]] || bad+=("$guc=$got(want $want)")
     done
     if ((${#bad[@]})); then echo "DRIFT ${bad[*]}"; exit 1; fi