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/stacks/userdata_belt_gate_test.go

@@ -10,8 +10,8 @@ import (
 // Creating ${USERDATA_PATH}/... then would land app data on the rootfs, shadowed when the drive returns.
 // Companion red-proof: removing the gate in ensureUserdataMounts makes the dir get created → this fails.
 func TestEnsureUserdataMounts_SkipsAbsentExternalDrive(t *testing.T) {
-	m := newMigManager(t, "")                            // sysDataPath = /mnt/sys_drive
-	m.isMountPoint = func(string) bool { return false }  // external drive is NOT mounted
+	m := newMigManager(t, "")                           // sysDataPath = /mnt/sys_drive
+	m.isMountPoint = func(string) bool { return false } // external drive is NOT mounted
 	stackDir := t.TempDir()
 	if err := os.WriteFile(filepath.Join(stackDir, "docker-compose.yml"), []byte(beltCompose), 0o644); err != nil {
 		t.Fatal(err)