Add runtime.stt.transcribeAudioFile for plugin STT access

Expose audio transcription through the PluginRuntime so external
plugins (e.g. marmot) can use openclaw's media-understanding provider
framework without importing unexported internal modules.

The new transcribeAudioFile() wraps runCapability({capability: "audio"})
and reads provider/model/apiKey from tools.media.audio in the config,
matching the pattern used by the Discord VC implementation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/plugins/runtime/index.ts

@@ -95,6 +95,7 @@ import { buildTemplateMessageFromPayload } from "../../line/template-messages.js
 import { getChildLogger } from "../../logging.js";
 import { normalizeLogLevel } from "../../logging/levels.js";
 import { convertMarkdownTables } from "../../markdown/tables.js";
+import { transcribeAudioFile } from "../../media-understanding/transcribe-audio.js";
 import { isVoiceCompatibleAudio } from "../../media/audio.js";
 import { mediaKindFromMime } from "../../media/constants.js";
 import { fetchRemoteMedia } from "../../media/fetch.js";
@@ -244,6 +245,7 @@ export function createPluginRuntime(): PluginRuntime {
     system: createRuntimeSystem(),
     media: createRuntimeMedia(),
     tts: { textToSpeechTelephony },
+    stt: { transcribeAudioFile },
     tools: createRuntimeTools(),
     channel: createRuntimeChannel(),
     logging: createRuntimeLogging(),

src/plugins/runtime/types.ts

@@ -25,6 +25,8 @@ type UpsertChannelPairingRequestForAccount = (
 type FetchRemoteMedia = typeof import("../../media/fetch.js").fetchRemoteMedia;
 type SaveMediaBuffer = typeof import("../../media/store.js").saveMediaBuffer;
 type TextToSpeechTelephony = typeof import("../../tts/tts.js").textToSpeechTelephony;
+type TranscribeAudioFile =
+  typeof import("../../media-understanding/transcribe-audio.js").transcribeAudioFile;
 type BuildMentionRegexes = typeof import("../../auto-reply/reply/mentions.js").buildMentionRegexes;
 type MatchesMentionPatterns =
   typeof import("../../auto-reply/reply/mentions.js").matchesMentionPatterns;
@@ -207,6 +209,9 @@ export type PluginRuntime = {
   tts: {
     textToSpeechTelephony: TextToSpeechTelephony;
   };
+  stt: {
+    transcribeAudioFile: TranscribeAudioFile;
+  };
   tools: {
     createMemoryGetTool: CreateMemoryGetTool;
     createMemorySearchTool: CreateMemorySearchTool;