feat: add Novita AI as LLM provider

[Alex-wuhu]

Summary

Add Novita AI as a new LLM provider. Novita offers an OpenAI-compatible API with competitive pricing and a wide selection of open-source models.

Changes

• New Novita provider following existing provider patterns
• API key configuration via NOVITA_API_KEY environment variable
• Support for chat, completion, and embedding models

Configuration

NOVITA_API_KEY=your_key_here

Endpoint: https://api.novita.ai/openai

[hijzy]

PR Review

This PR adds Novita AI as a new embedding provider by routing it through the existing OpenAI-compatible endpoint. The addition itself is minimal and follows the established pattern for providers like zhipu, siliconflow, and bailian — it simply adds "novita" as a new case in the embedding switch statement.

However, it also includes larger changes to index.ts and postinstall.cjs that improve native module loading robustness (ESM createRequire, isPathInside security check via realpathSync, shell: false for spawn calls, Windows npm.cmd support, path normalization for \\?\\ prefixes). These improvements are solid.

Notable issue: There is a duplicated const startMs and const result block in postinstall.cjs for the better-sqlite3 rebuild that will cause a runtime error. This duplicate appears right after the new npmCmd-based rebuild call, creating conflicting variable declarations.

此 PR 将 Novita AI 添加为新的嵌入提供者，改动很小且遵循已有的 provider 模式。但还包含了 index.ts 和 postinstall.cjs 的原生模块加载改进。值得注意的是，postinstall.cjs 中 better-sqlite3 rebuild 代码块被重复声明了两次（const startMs 和 const result），会导致运行时报错。

• Safety: ⚠️ Duplicate code bug in postinstall
• Mergeable: After fixing the duplicate
• Confidence: 3/5

[hijzy]

🔧 Suggested Fix

Remove the duplicate better-sqlite3 rebuild block in postinstall.cjs. Around line 392, the old const startMs = Date.now(); and const result = spawnSync("npm", ...) still exist alongside the new npmCmd-based version added just above. Delete the old block (lines starting from the second const startMs through the closing of the old spawnSync call) to resolve the conflicting variable declarations.

🔧 修改建议

删除 postinstall.cjs 中重复的 better-sqlite3 rebuild 代码块。在第 392 行附近，旧的 const startMs = Date.now(); 和 const result = spawnSync("npm", ...) 仍然存在于新添加的 npmCmd 版本之后。删除旧代码块（从第二个 const startMs 开始到旧的 spawnSync 调用结束）即可解决变量声明冲突。