feat: add log source

[swrzalek]

Summary

• Prefixes all API error messages and logs with their source (e.g., [Anthropic API], [Exa API],
  [Financial Datasets API])
• Adds identifyProvider() helper to identify LLM providers based on model name
• Updates withRetry() to log errors with provider context
• Standardizes error message format across all external API integrations

Before:

Error: [GoogleGenerativeAI Error]: Error fetching from
https://generativelanguage.googleapis.com/v1beta/models/gemini-3-flash-preview:generateContent: [400 Bad
Request] API key not valid. Please pass a valid API key. [{"@type":"type.googleapis.com/google.rpc.ErrorIn
fo","reason":"API_KEY_INVALID","domain":"googleapis.com","metadata":{"service":"generativelanguage.googlea
pis.com"}},{"@type":"type.googleapis.com/google.rpc.LocalizedMessage","locale":"en-US","message":"API key
not valid. Please pass a valid API key."}]

After:

[ERROR [Google API] error (attempt 1/3): [GoogleGenerativeAI Error]: Error fetching from               │
│       https://generativelanguage.googleapis.com/v1beta/models/gemini-3-flash-preview:generateContent:  │
│       [400 Bad Request] API key not valid. Please pass a valid API key.                                │
│       [{"@type":"type.googleapis.com/google.rpc.ErrorInfo","reason":"API_KEY_INVALID","domain":"google │
│       apis.com","metadata":{"service":"generativelanguage.googleapis.com"}},{"@type":"type.googleapis. │
│       com/google.rpc.LocalizedMessage","locale":"en-US","message":"API key not valid. Please pass a    │
│       valid API key."}]                                                                                │
│ [ERROR [Google API] error (attempt 2/3): [GoogleGenerativeAI Error]: Error fetching from               │
│       https://generativelanguage.googleapis.com/v1beta/models/gemini-3-flash-preview:generateContent:  │
│       [400 Bad Request] API key not valid. Please pass a valid API key.                                │
│       [{"@type":"type.googleapis.com/google.rpc.ErrorInfo","reason":"API_KEY_INVALID","domain":"google │
│       apis.com","metadata":{"service":"generativelanguage.googleapis.com"}},{"@type":"type.googleapis. │
│       com/google.rpc.LocalizedMessage","locale":"en-US","message":"API key not valid. Please pass a    │
│       valid API key."}]                                                                                │
│ [ERROR [Google API] error (attempt 3/3): [GoogleGenerativeAI Error]: Error fetching from               │
│       https://generativelanguage.googleapis.com/v1beta/models/gemini-3-flash-preview:generateContent:  │
│       [400 Bad Request] API key not valid. Please pass a valid API key.                                │
│       [{"@type":"type.googleapis.com/google.rpc.ErrorInfo","reason":"API_KEY_INVALID","domain":"google │
│       apis.com","metadata":{"service":"generativelanguage.googleapis.com"}},{"@type":"type.googleapis. │
│       com/google.rpc.LocalizedMessage","locale":"en-US","message":"API key not valid. Please pass a    │
│       valid API key."}]