style: gofmt normalization — no logic changes

gofmt -w across the controller tree (46 files) so gofmt -l is empty — disarms the
formatting landmine where a targeted edit + accidental gofmt -w swept ~46 unrelated
files. Pure formatting: whitespace + gofmt's optional-semicolon removal in reflowed
inline closures. One doc comment reworded ('' -> 'the empty string') to avoid gofmt's
Go-1.19 doc-comment typographic substitition ('' -> curly quote) muddying its meaning.
No build/vet/test behavior change.

controller/internal/web/export_download_test.go

@@ -50,13 +50,13 @@ func TestFabDownload_TraversalGuardAndCleanup(t *testing.T) {
 	}
 
 	refused := []string{
-		"..%2Fdecoy.fab",            // ../decoy.fab
-		"..%5Cdecoy.fab",            // ..\decoy.fab
-		"%2Fetc%2Fpasswd",           // absolute path
-		"sub%2Fx.fab",               // separator
-		"..",                        // bare traversal
-		".hidden.fab",               // not the exporter's naming (leading dot)
-		"x.txt",                     // not a .fab
+		"..%2Fdecoy.fab",  // ../decoy.fab
+		"..%5Cdecoy.fab",  // ..\decoy.fab
+		"%2Fetc%2Fpasswd", // absolute path
+		"sub%2Fx.fab",     // separator
+		"..",              // bare traversal
+		".hidden.fab",     // not the exporter's naming (leading dot)
+		"x.txt",           // not a .fab
 	}
 	for _, f := range refused {
 		if rr := fetchDownload(s, f); rr.Code != http.StatusBadRequest {