feat: add Moonshot AI (Kimi) provider and update xAI Grok models (#1953)

- Add comprehensive Moonshot AI provider with 11 models including:
  * Legacy moonshot-v1 series (8k, 32k, 128k context)
  * Latest Kimi K2 models (K2 Preview, Turbo, Thinking)
  * Vision-enabled models for multimodal capabilities
  * Auto-selecting model variants

- Update xAI provider with latest Grok models:
  * Add Grok 4 (256K context) and Grok 4 (07-09) variant
  * Add Grok 3 Mini Beta and Mini Fast Beta variants
  * Update context limits to match actual model capabilities
  * Remove outdated grok-beta and grok-2-1212 models

- Add MOONSHOT_API_KEY to environment configuration
- Register Moonshot provider in service status monitoring
- Full OpenAI-compatible API integration via api.moonshot.ai
- Fix TypeScript errors in GitHub provider

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

app/lib/.server/llm/constants.ts

@@ -1,18 +1,19 @@
 /*
- * Maximum tokens for response generation (conservative default for older models)
- * Modern models can handle much higher limits - specific limits are set per model
+ * Maximum tokens for response generation (updated for modern model capabilities)
+ * This serves as a fallback when model-specific limits are unavailable
+ * Modern models like Claude 3.5, GPT-4o, and Gemini Pro support 128k+ tokens
  */
-export const MAX_TOKENS = 32000;
+export const MAX_TOKENS = 128000;
 
 /*
  * Provider-specific default completion token limits
  * Used as fallbacks when model doesn't specify maxCompletionTokens
  */
 export const PROVIDER_COMPLETION_LIMITS: Record<string, number> = {
-  OpenAI: 16384,
-  Github: 16384, // GitHub Models use OpenAI-compatible limits
-  Anthropic: 128000,
-  Google: 32768,
+  OpenAI: 4096, // Standard GPT models (o1 models have much higher limits)
+  Github: 4096, // GitHub Models use OpenAI-compatible limits
+  Anthropic: 64000, // Conservative limit for Claude 4 models (Opus: 32k, Sonnet: 64k)
+  Google: 8192, // Gemini 1.5 Pro/Flash standard limit
   Cohere: 4000,
   DeepSeek: 8192,
   Groq: 8192,