fix(plugins): 分片 VM 拿不到插件配置

页面探测走的是 fanout（分片）路径，结果写回走共享 VM。分片 VM 从同一份
源码启动，但没有 state 文件、没有插件身份，所以 PLUGIN.prices（配置，不是
累计状态）在分片里是空的。

对只读累计状态的插件无所谓；对按配置分支的插件就是致命的。OpenDesign
适配器读 prices.control_key，未播种时它对每个主机都得出「未配置」并报
skip，而同一个调用走共享 VM 是好的。也就是说：生产上死、所有调共享 VM 的
测试全绿。

pool 在每次取用时推送配置（不只是首次启动时），并把配置变化也带给池中
复用的 VM；推送是拷贝，分片拿不到共享表的引用。

这条不是在写代码时想到的，是端到端验证时撞出来的：单元测试全过，隔离实例
打真上游时 vela 报「未配置」，而 control_key 明明写进去了。

(cherry picked from commit 65075b6d44)

internal/lua/plugins.go

@@ -1172,6 +1172,54 @@ func audienceAllows(want, role string) bool {
 // upgrade would overwrite anyway.
 type visibilityOverrides map[string]string
 
+// seedShardConfig copies the shared plugin's `prices` table onto a shard VM.
+//
+// `prices` is CONFIGURATION, as opposed to `state` (accumulated history). A shard
+// must not write state — its copy is thrown away — but it must be able to READ
+// the operator's configuration, or a plugin that branches on its configuration
+// behaves one way through Plugins.Call and another through ShardCall.
+//
+// Found by the OpenDesign adapter, which reads prices.control_key: without this, a
+// fanout probe saw an empty table, concluded "not configured", and reported a
+// skip for every host — while the identical call through the shared VM worked.
+// The page uses the fanout path, so the feature would have been dead in
+// production and alive in every test that called the shared VM.
+//
+// Called on every checkout (boot and reuse), so a configuration change reaches
+// pooled VMs too. The push is a copy: shards get the same values, never a live
+// reference to the shared table.
+func (ps *Plugins) seedShardConfig(name string, w *worker) {
+	if ps == nil || w == nil || w.L == nil {
+		return
+	}
+	ps.mu.RLock()
+	p := ps.find(name)
+	ps.mu.RUnlock()
+	if p == nil {
+		return
+	}
+	p.mu.Lock()
+	if p.state == nil || p.state.L == nil || p.state.L == w.L {
+		p.mu.Unlock()
+		return
+	}
+	prices := snapshotField(p.state.L, "prices")
+	p.mu.Unlock()
+	if prices == nil {
+		return
+	}
+	L := w.L
+	L.SetTop(0)
+	defer L.SetTop(0)
+	L.GetGlobal(pluginGlobal)
+	if L.IsNil(-1) {
+		return
+	}
+	plug := L.GetTop()
+	pushGoValue(L, prices)
+	L.SetField(plug, "prices")
+}
+
 // SetPluginVisibility records an operator override for a plugin's audience. An
 // empty value clears the override and restores the plugin's own default.
 func (ps *Plugins) SetPluginVisibility(plugin, audience string) {