feat(ai): add Qwen Token Plan as built-in provider (#6858)

Add Alibaba Cloud Model Studio Token Plan subscription service as two
built-in API-key providers: qwen-token-plan (international, Singapore)
and qwen-token-plan-cn (China, Beijing).

Each provider exposes 15 text-generation models (Qwen, DeepSeek, GLM,
Kimi, MiniMax) via the OpenAI-compatible endpoint with DashScope
enable_thinking support. Model metadata is sourced from models.dev;
qwen3.8-max-preview is hardcoded until models.dev includes it.

Also fixes kimi-coding test references (k2p7 -> kimi-for-coding) after
models.dev catalog update picked up by generate-models.

Closes #6850

packages/coding-agent/src/cli/args.ts

@@ -362,6 +362,8 @@ ${chalk.bold("Environment Variables:")}
   CLOUDFLARE_API_KEY               - Cloudflare API token (Workers AI and AI Gateway)
   CLOUDFLARE_ACCOUNT_ID            - Cloudflare account id (required for both)
   CLOUDFLARE_GATEWAY_ID            - Cloudflare AI Gateway slug (required for AI Gateway)
+  QWEN_TOKEN_PLAN_API_KEY          - Qwen Token Plan API key (international region)
+  QWEN_TOKEN_PLAN_CN_API_KEY       - Qwen Token Plan API key (China region)
   XIAOMI_API_KEY                   - Xiaomi MiMo API key (api.xiaomimimo.com billing)
   XIAOMI_TOKEN_PLAN_CN_API_KEY     - Xiaomi MiMo Token Plan API key (China region)
   XIAOMI_TOKEN_PLAN_AMS_API_KEY    - Xiaomi MiMo Token Plan API key (Amsterdam region)

packages/coding-agent/src/core/model-resolver.ts

@@ -44,6 +44,8 @@ export const defaultModelPerProvider: Record<KnownProvider, string> = {
 	"kimi-coding": "kimi-for-coding",
 	"cloudflare-workers-ai": "@cf/moonshotai/kimi-k2.6",
 	"cloudflare-ai-gateway": "workers-ai/@cf/moonshotai/kimi-k2.6",
+	"qwen-token-plan": "qwen3.7-max",
+	"qwen-token-plan-cn": "qwen3.7-max",
 	xiaomi: "mimo-v2.5-pro",
 	"xiaomi-token-plan-cn": "mimo-v2.5-pro",
 	"xiaomi-token-plan-ams": "mimo-v2.5-pro",