device_extensions and rule_module are read, and were reported as unsupported

同一个解析器往上约四十行就把这两个键读进 `featureDeviceExtensions` 与
`featureRuleModule`,prepare 在消费者激活该 feature 时会读它们 —— 它们正是「新增一门
设备语言不需要引擎发版」的全部依据。它们只是没被加进 `kKnownFeatureKeys`,于是引擎对
一个它刚刚用过的键打印:

    [features].rules-spirv has unsupported key 'rule_module' (ignored).
    Supported keys: defines, flags, forward, implies, provides, requires, sources.

比消息错更坏:它在**建议包作者删掉让规则生效的那两行**。

没被发现,是因为规则包平时走的 host-module 路径不打印 schema 警告;而**普通**构建会
打印。当一个规则包开始产出 `tools = [...]` 要的二进制,它的普通构建就成了常态,这条
噪音于是浮到每个用户面前。

Author: speak-agent

modules/manifest/src/toml.cppm

@@ -837,6 +837,25 @@ std::expected<Manifest, ManifestError> parse_string(std::string_view content,
                 static constexpr std::string_view kKnownFeatureKeys[] = {
                     "defines", "flags", "forward", "implies", "provides",
                     "requires", "sources",
+                    // THE TWO RULE-PACKAGE KEYS, WHICH THIS PARSER READS ABOUT
+                    // FORTY LINES ABOVE AND THEN REPORTED AS UNSUPPORTED.
+                    //
+                    // `device_extensions` and `rule_module` are parsed into
+                    // `featureDeviceExtensions` and `featureRuleModule`, and
+                    // read by prepare when a consumer activates the feature --
+                    // they are the whole reason a new device language costs no
+                    // engine release. Leaving them off this list made every
+                    // ordinary load of such a package print "unsupported key
+                    // (ignored)" for a key it had just used, which is worse
+                    // than a wrong message: it tells a package author to delete
+                    // the two lines that make their rule work.
+                    //
+                    // It went unnoticed because the host-module path a rule
+                    // package is normally loaded through does not print schema
+                    // warnings. An ORDINARY build of the same package does --
+                    // and `tools = [...]` made ordinary builds of rule packages
+                    // routine.
+                    "device_extensions", "rule_module",
                 };
                 for (auto& [fkey, fignored] : fval.as_table()) {
                     (void)fignored;