Run gofmt over the seven files that had drifted

Formatting only: import order, and statements that were packed onto one
line split out. `git diff -w` shows nothing but that.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CGeSZxh1DCtRxmFVSYVGvJ

internal/llm/client_test.go

@@ -19,7 +19,7 @@ func TestComplete(t *testing.T) {
 			t.Errorf("path = %q, want /v1/chat/completions", r.URL.Path)
 		}
 		var reqBody struct {
-			Messages  []struct {
+			Messages []struct {
 				Role    string `json:"role"`
 				Content string `json:"content"`
 			} `json:"messages"`