Hard restore with X drops staged pins at every depth

X restores the selection to the committed pins without the staged or
committed question, and resets every restored repository's index to
HEAD, so staged pins below are dropped too. Dropped staged pins alone
don't make it ask; they are listed if something else is lost.

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

internal/submodule/provider.go

@@ -72,15 +72,24 @@ type Switcher interface {
 	Switch(ctx context.Context, path string, b Branch) (string, error)
 }
 
-// RestoreTarget is the pin a submodule is restored to. It doesn't matter for
-// the superproject, whose target is always HEAD.
+// RestoreTarget is the pin a submodule is restored to, and whether staged
+// pins below it are kept. The superproject's target is always HEAD; only
+// RestoreHard matters for it.
 type RestoreTarget int
 
 const (
 	RestoreStaged    RestoreTarget = iota // the pin in the parent's index: a staged pin is kept and used
 	RestoreCommitted                      // the pin in the parent's HEAD: a staged pin is unstaged
+	RestoreHard                           // the pin in the parent's HEAD, and staged pins below are dropped too
 )
 
+// Committed reports whether a submodule goes to the pin in its parent's HEAD.
+func (t RestoreTarget) Committed() bool { return t != RestoreStaged }
+
+// KeepsStaged reports whether staged pins below the restored repository are
+// kept.
+func (t RestoreTarget) KeepsStaged() bool { return t != RestoreHard }
+
 // Loss is what a restore discards. The zero Loss means nothing is lost.
 type Loss struct {
 	Files        int // changed, conflicted and untracked files and directories