feat(usage): add Kimi and DeepSeek usage handlers

Wire /v1/usages for Kimi (OAuth + API key) and balance API for DeepSeek,
flag both providers with usage/usageApikey, and normalize their quotas
in the dashboard ProviderLimits parser.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/unit/usage-dispatch.test.js

@@ -15,7 +15,8 @@ const load = () => import("../../open-sse/services/usage.js");
 const SUPPORTED = [
   "github", "gemini-cli", "antigravity", "claude", "codex", "kiro",
   "qoder", "qwen", "iflow", "ollama", "glm", "glm-cn",
-  "minimax", "minimax-cn", "vercel-ai-gateway", "grok-cli",
+  "minimax", "minimax-cn", "vercel-ai-gateway", "grok-cli", "kimi",
+  "deepseek",
 ];
 
 describe("usage dispatch", () => {