feat(voice): rework TTS/ASR stack and unify tool/skill config schema

docs/en/models/qianfan.mdx

@@ -40,7 +40,7 @@ To force a specific Vision model, set it explicitly in `config.json`:
 
 ```json
 {
-  "tool": {
+  "tools": {
     "vision": {
       "model": "ernie-4.5-turbo-vl"
     }

docs/en/releases/v2.0.7.mdx

@@ -11,7 +11,7 @@ New built-in `image-generation` skill supporting text-to-image, image-to-image,
 - **Zero model selection**: Just configure an API key and it works — no need to manually specify a model. You can also name a specific model in conversation (e.g. "draw a cat with seedream")
 - **Flexible control**: Supports `quality`, `size` (512/1K–4K), and `aspect_ratio` parameters, with each provider automatically mapping to its supported values
 - **Image editing**: Pass existing images for editing, style transfer, or multi-image fusion (Seedream supports up to 14 reference images)
-- **Skill-level config**: Pin a default model via `skill.image-generation.model` in `config.json`
+- **Skill-level config**: Pin a default model via `skills.image-generation.model` in `config.json`
 - **Image lightbox**: All images in the Web console now support click-to-enlarge preview
 
 Docs: [Image Generation Skill](https://docs.cowagent.ai/en/skills/image-generation)

docs/en/releases/v2.0.8.mdx

@@ -51,7 +51,7 @@ The voice and streaming building blocks come from a community contribution #2791
 
 ## 🔧 Tools and Safety
 
-- **Vision model selection**: `tool.vision.model` config now actually takes effect, with automatic fallback when unconfigured #2792
+- **Vision model selection**: `tools.vision.model` config now actually takes effect, with automatic fallback when unconfigured #2792
 - **Bash safety prompt**: The destructive-deletion confirm prompt is now scoped to paths outside the workspace — routine in-workspace operations are no longer interrupted
 
 ## 🐛 Other Fixes

docs/en/skills/image-generation.mdx

@@ -87,7 +87,7 @@ Configure ARK_API_KEY as xxx
 To force all image generation through a specific provider's model, add this to `config.json`:
 
 ```json
-"skill": {
+"skills": {
   "image-generation": {
     "model": "seedream-5.0-lite"
   }

docs/en/tools/vision.mdx

@@ -51,7 +51,7 @@ To specify a particular model for the vision tool, add to `config.json`:
 
 ```json
 {
-    "tool": {
+    "tools": {
         "vision": {
             "model": "ernie-4.5-turbo-vl"
         }