[audio] split audio::AudioResourceId off as independent alias with conversion helper

audio::AudioResourceId is now an independent std::string alias (was a
re-export of muse::audioplugins::PluginResourceId). Add
toAudioResourceId / toAudioResourceIdList helpers in audio/common/
audiotypes.h - documenting the seam between plugin-identity and
audio-pipeline-resource roles. One-directional today: both aliases
bottom out at std::string so the conversion is one-to-one; the helper
becomes a real bridge if either side later gains a strong wrapper.

A static_assert in audioresourcetypes_tests.cpp pins the underlying-
std::string contract; a new ToAudioResourceIdRoundTrips test exercises
the helper end-to-end.

VST and audio-engine resolvers stay on audio::AudioResourceId
unchanged - structurally pinned by abstractfxresolver and keeps the
Audacity surface unaffected.

Author: luapmartin

framework/audio/common/audiotypes.h

@@ -171,8 +171,23 @@ struct AudioEngineConfig {
 using AudioSourceName = std::string;
 using AudioUnitConfig = std::map<std::string, std::string>;
 
-using AudioResourceId = muse::audioplugins::PluginResourceId;
-using AudioResourceIdList = muse::audioplugins::PluginResourceIdList;
+// AudioResourceId addresses a resource within the audio pipeline;
+// audioplugins::PluginResourceId is a plugin's identity in the cache.
+// Both alias std::string today and convert one-to-one - the seam is
+// documentary so the two roles do not drift.
+using AudioResourceId = std::string;
+using AudioResourceIdList = std::vector<AudioResourceId>;
+
+inline AudioResourceId toAudioResourceId(const muse::audioplugins::PluginResourceId& id)
+{
+    return id;
+}
+
+inline AudioResourceIdList toAudioResourceIdList(const muse::audioplugins::PluginResourceIdList& ids)
+{
+    return AudioResourceIdList(ids.begin(), ids.end());
+}
+
 using AudioResourceVendor = muse::audioplugins::AudioResourceVendor;
 using AudioResourceAttributes = muse::audioplugins::AudioResourceAttributes;
 using AudioResourceMeta = muse::audioplugins::AudioResourceMeta;

framework/audio/tests/audioresourcetypes_tests.cpp

@@ -31,6 +31,12 @@
 
 using namespace muse;
 
+// Document the underlying types behind the named seam between the audio and
+// audioplugins resource ids. If either becomes a strong wrapper later, this
+// assert fires and the migration is deliberate.
+static_assert(std::is_same_v<audio::AudioResourceId, std::string>);
+static_assert(std::is_same_v<audioplugins::PluginResourceId, std::string>);
+
 // The on-disk plugin cache stores AudioResourceMeta::type as the canonical
 // wire string. These strings must stay stable across releases — caches written
 // by older builds must remain readable. Each plugin module owns its own copy
@@ -89,3 +95,23 @@ TEST(Audio_AudioResourceTypes, IsResourceTypeHelper)
     EXPECT_FALSE(audio::isResourceType(meta, audio::AudioResourceType::VstPlugin));
     EXPECT_TRUE(audio::isResourceType(meta, audio::AudioResourceType::Undefined));
 }
+
+// audio::toAudioResourceId is the documentary seam between the audioplugins
+// module's PluginResourceId and the audio module's AudioResourceId. Today
+// the conversion is one-to-one because both alias std::string; if either
+// side later gains a real wrapper, this round-trip becomes a real one and
+// this test is where it gets verified.
+TEST(Audio_AudioResourceTypes, ToAudioResourceIdRoundTrips)
+{
+    const audioplugins::PluginResourceId plugId = "Muse Reverb";
+    const audio::AudioResourceId audioId = audio::toAudioResourceId(plugId);
+    EXPECT_EQ(audioId, plugId);
+    EXPECT_EQ(audioId, "Muse Reverb");
+
+    const audioplugins::PluginResourceIdList plugIds = { "A", "B", "C" };
+    const audio::AudioResourceIdList audioIds = audio::toAudioResourceIdList(plugIds);
+    ASSERT_EQ(audioIds.size(), plugIds.size());
+    for (size_t i = 0; i < plugIds.size(); ++i) {
+        EXPECT_EQ(audioIds[i], plugIds[i]);
+    }
+}