Claude/custom provider connection 011o7 p9 an2oat gcc hyj n8msk - #4652

…er system

This commit completes the integration of corporate networking features into the main provider system.

Changes to config.ts:
- Extended provider options schema to include proxy, proxyAuth, and tls configuration
- Added support for proxy: "auto" | string | false
- Added proxyAuth with username/password (supports {env:VAR} substitution)
- Added tls configuration for CA certificates (single file or array), client certificates, and validation control
- All new options are optional and backward compatible

Changes to provider.ts:
- Modified getSDK() function to detect when corporate networking is needed
- When proxy or tls options are present, uses createCorporateFetch() instead of standard fetch
- Preserves existing timeout-wrapped fetch for providers without corporate networking requirements
- Enables interactive proxy authentication prompts
- Backward compatible with existing provider configurations

Features now available:
✅ Auto-detect proxy from HTTP_PROXY/HTTPS_PROXY environment variables and system settings
✅ Interactive proxy authentication prompts (browser-like experience)
✅ Support for CA certificate bundles with multiple certificates
✅ Client certificate authentication (mutual TLS)
✅ Configurable certificate validation
✅ Full backward compatibility

Usage example:
```jsonc
{
  "provider": {
    "corporate-ai": {
      "npm": "@ai-sdk/openai-compatible",
      "api": "https://ai.company.com/v1",
      "options": {
        "apiKey": "{env:CORPORATE_AI_KEY}",
        "proxy": "auto",
        "tls": {
          "ca": "/etc/ssl/certs/corporate-ca-bundle.crt"
        }
      }
    }
  }
}
```

Related files:
- proxy-detection.ts: Auto-detection logic
- proxy-auth.ts: Interactive authentication
- corporate-fetch.ts: Main integration point
- CORPORATE_INTEGRATION_EXAMPLE.md: Integration guide
- CORPORATE_PROXY_FEATURE_SUMMARY.md: Feature documentation

…atGCCHyjN8msk