Anthropic Messages adapter (#40)

Co-authored-by: dev_agent <dev_agent@cubecraftlabs.com>
Co-committed-by: dev_agent <dev_agent@cubecraftlabs.com>

internal/ai/llm/errors.go

@@ -58,6 +58,9 @@ func (e *RateLimitedError) Error() string {
 	return fmt.Sprintf("%s: retry after %v", ErrRateLimited, e.RetryAfter)
 }
 
+// GoString keeps %#v to the redacted Error text instead of the fields.
+func (e *RateLimitedError) GoString() string { return e.Error() }
+
 // Is reports whether target is ErrRateLimited.
 func (e *RateLimitedError) Is(target error) bool { return target == ErrRateLimited }
 
@@ -128,5 +131,9 @@ func (e *ProviderError) Body() string { return e.body }
 
 func (e *ProviderError) Error() string { return e.text }
 
+// GoString keeps %#v to the redacted Error text instead of the fields,
+// whose names could spell the credential.
+func (e *ProviderError) GoString() string { return e.text }
+
 // Is reports whether target is ErrProvider.
 func (e *ProviderError) Is(target error) bool { return target == ErrProvider }