style: gofmt struct-tag alignment across v0 files

v0 landed with a few misaligned struct tags and fields; gofmt -l
flagged categories.go, topics.go, discourse_test.go and the smoke
fake. Alignment only, no behavior change, so the tree passes the
gofmt gate cleanly.

discourse_test.go

@@ -82,15 +82,15 @@ func newFake(t *testing.T) *fakeDiscourse {
 			}
 			if req.Name == "denied" { // simulate a non-admin key
 				writeJSON(w, 403, map[string]any{
-					"errors":              []string{"You are not permitted to view the requested resource."},
-					"error_description":   "Access denied",
+					"errors":            []string{"You are not permitted to view the requested resource."},
+					"error_description": "Access denied",
 				})
 				return
 			}
 			f.mu.Lock()
 			cat := Category{
 				ID: f.nextCat, Name: req.Name,
-				Slug: strings.ToLower(strings.ReplaceAll(req.Name, " ", "-")),
+				Slug:  strings.ToLower(strings.ReplaceAll(req.Name, " ", "-")),
 				Color: req.Color, TextColor: req.TextColor, Position: req.Position,
 			}
 			f.nextCat++
@@ -158,7 +158,7 @@ func newFake(t *testing.T) *fakeDiscourse {
 		case http.MethodPut:
 			var body struct {
 				Post struct {
-					Raw       string `json:"raw"`
+					Raw        string `json:"raw"`
 					EditReason string `json:"edit_reason"`
 				} `json:"post"`
 			}