Add support for multiple Anthropic API keys

This change introduces the ability to use a secondary Anthropic API key
(ANTHROPIC_API_KEY2) in addition to the primary one. The system now
randomly selects between the two keys when making API calls, which can
help distribute load and potentially avoid rate limiting issues.

The env.mjs file has been updated to include the new ANTHROPIC_API_KEY2
environment variable, ensuring proper validation and type checking.

Author: jahooma

backend/src/claude.ts

@@ -38,7 +38,8 @@ export const promptClaudeStream = async function* (
     ignoreHelicone = false,
   } = options
 
-  const apiKey = env.ANTHROPIC_API_KEY
+  const apiKey =
+    Math.random() > 0.5 ? env.ANTHROPIC_API_KEY : env.ANTHROPIC_API_KEY2
 
   if (!apiKey) {
     throw new Error('Missing ANTHROPIC_API_KEY')

backend/src/env.mjs

@@ -16,6 +16,7 @@ dotenv.config({ path })
 export const env = createEnv({
   server: {
     ANTHROPIC_API_KEY: z.string().min(1).startsWith('sk-ant-'),
+    ANTHROPIC_API_KEY2: z.string().min(1).startsWith('sk-ant-'),
     HELICONE_API_KEY: z.string().min(1).startsWith('pk-helicone-'),
     OPEN_AI_KEY: z.string().min(1).startsWith('sk-proj-'),
     STRIPE_SECRET_KEY: z.string().min(1),