fix(acceptance): 按自适应容量执行单节点压测

修正单节点验收将 hard limit 等同空闲分配容量的问题，从冷启动容量 4 开始逐级加压，并要求实际分配容量和运行任务峰值均达到目标后才计入稳定并发。\n\n异常退出时同步清理模拟器和回调收集器资源。已执行 bash -n、ShellCheck 和 production acceptance 脚本测试。

tests/release/production-acceptance-script-test.sh

@@ -67,6 +67,15 @@ awk '
 # shellcheck source=/dev/null
 source "$tmp/admin-request.sh"
 
+awk '
+  /^single_node_capacity_ready\(\)/ { capture = 1 }
+  capture && /^install_single_node_load_driver\(\)/ { exit }
+  capture { print }
+' "$script" >"$tmp/single-node-capacity.sh"
+
+# shellcheck source=/dev/null
+source "$tmp/single-node-capacity.sh"
+
 cluster_root=$tmp/repository
 git init -q "$cluster_root"
 git -C "$cluster_root" config user.name 'Acceptance Script Test'
@@ -216,6 +225,23 @@ admin_request POST /api/admin/system/acceptance/runs/test-run/finish "$admin_bod
 [[ $(jq -r '.status' "$admin_output") == failed ]]
 [[ $(<"$admin_attempts") == 3 ]]
 
+single_node_capacity_ready '1:8:4:4:normal' 8
+single_node_capacity_ready '1:8:8:8:busy' 8
+for invalid_capacity_state in \
+  '0:8:4:4:normal' \
+  '1:7:4:4:normal' \
+  '1:8:0:4:normal' \
+  '1:8:9:4:normal' \
+  '1:8:4:0:normal' \
+  '1:8:4:9:normal' \
+  '1:8:4:4:critical' \
+  '1:8:4:4:normal:extra'; do
+  if single_node_capacity_ready "$invalid_capacity_state" 8; then
+    echo "unsafe single-node capacity state passed: $invalid_capacity_state" >&2
+    exit 1
+  fi
+done
+
 passing_pressure_row='2026-08-01T00:00:00Z,0,0,899,149,200,84,1535,0,32,32,0,0,0,0,2,48,0,8,8,0,0,0,16,16,0,0,1535,100'
 pressure_row_passes_live_gates "$passing_pressure_row"
 [[ $(pressure_row_live_gate_reason '2026-08-01T00:00:00Z,0,0,900,149,200,79,1535,0,32,32,0,0,0,0,2,48,0,8,8,0,0,0,16,16,0,0,1535,100') == \