DeepSeek connector: add V4 models (deepseek-v4-pro / deepseek-v4-flash)

[leaft]

What

Add DeepSeek's current V4 models to the DeepSeek BYOK connector and make deepseek-v4-flash the recommended default, while keeping the existing deepseek-chat / deepseek-r1 options for backward compatibility.

-    defaultModel: 'deepseek-chat',
-    models: ['deepseek-chat', 'deepseek-r1'],
+    defaultModel: 'deepseek-v4-flash',
+    models: ['deepseek-v4-pro', 'deepseek-v4-flash', 'deepseek-chat', 'deepseek-r1'],

Why

The DeepSeek connector only offered the legacy deepseek-chat / deepseek-r1 models. Because the model picker for non-Ollama providers is a fixed <select> populated solely from provider.models, users had no way to select DeepSeek's current V4 models (deepseek-v4-pro, deepseek-v4-flash) per the official API docs.

Closes #103.

Verification

• DeepSeek API direct: POST https://api.deepseek.com/chat/completions with model: "deepseek-v4-pro" → HTTP 200, response echoes "model":"deepseek-v4-pro".
• Full lrc path (lrc ui → /api/ui/connectors/validate-key → LiveReview cloud → DeepSeek):
  • deepseek-v4-pro → {"valid":true}
  • deepseek-v4-flash (implicitly via default) — accepted
  • bogus model id → {"valid":false} (control: confirms the cloud actually probes the model, not just the key)
• go build ./... and node --check providers.js pass.

Scope

UI-only change to internal/staticserve/static/ui-connectors/providers.js; no backend changes.

[shrsv]

Hi @leaft - thanks for the contribution.

We will have a discussion about updating model names on a day to day basis from some source such as OpenRouter or such. This way - the outdated model problem can be eliminated in a general way.

If it's going to take a while to integrate that approach - we will merge your changes for the short term.