form(
content,opts) ->results,action
Display an interactive form dialog with labeled input fields
Opens a bordered dialog with one input field per label in content.
The opts.meta table can specify per-field options like w (width)
and secret (mask input). The opts.values table pre-fills fields
(label to initial value), making the form usable for editing.
Returns a table mapping labels to values, plus an action string:
"save" when confirmed with CTRL+s, "cancel" when dismissed with
ESC. A cancelled form returns the initial values untouched, discarding
any edits made in the dialog.