Rules: placed in the same change they are created in

hc rule add --before/--after/--first created the rule at the end of its
chain and then moved it: two history entries, two probations, the rule
briefly in force in the wrong place, and in a changeset the place was
lost. POST /rules (and the other ordered kinds) now takes ?before=ID,
?after=ID or ?first=1, kept with the operation when staged.

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

internal/model/changeset.go

@@ -53,7 +53,10 @@ type Op struct {
 	ID int64 `json:"id,omitempty"`
 	// Data is the object (create), the fields to change (update,
 	// settings) or where to move it (move).
-	Data    json.RawMessage `json:"data,omitempty"`
+	Data json.RawMessage `json:"data,omitempty"`
+	// Place is where a create puts the object in its order (a move's
+	// data); none: at the end.
+	Place   json.RawMessage `json:"place,omitempty"`
 	Summary string          `json:"summary"`
 	AddedAt time.Time       `json:"added_at"`
 }