Wire retrying Provider into presets.FromSettings

FromSettings now returns llm.NewRetrying around the configured adapter,
so every Provider it builds retries transient Generate failures and gets
the default timeout; ListModels and Verify pass through.

The test recording transport now answers 400 instead of failing the
round trip: the ollama adapter reports a transport failure as
ErrTimeout, which is retried, so the helper would see three requests.

Tests: a 429 then 200 succeeds on the second request; exhausted retries
return ErrProvider after MaxRetries+1 requests with no key in any error.

Maestro task: 1a882923-fdb4-4576-ab82-9529e9974b26

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/ai/llm/presets/presets.go

@@ -178,13 +178,14 @@ var all = map[string]Preset{
 //
 // The Provider sends s.Temperature with every request whose Temperature is
 // nil; a request that sets one keeps it. Neither is sent to a model the
-// preset's OmitTemperature matches.
+// preset's OmitTemperature matches. It is wrapped in llm.NewRetrying, so
+// Generate retries transient vendor failures and has the default timeout.
 func FromSettings(s llm.Settings, key string) (llm.Provider, error) {
 	cp, err := fromSettings(s, key)
 	if err != nil {
 		return nil, redact(err, key)
 	}
-	return cp, nil
+	return llm.NewRetrying(cp), nil
 }
 
 func fromSettings(s llm.Settings, key string) (*configured, error) {