Text parameters: a vertical tab is a forced line break

frame.create, story.setText, text.insert and the other commands that take
text kept U+000B as a character, drawn as a missing-glyph box. It is the
forced line break of Word and PowerPoint text (Chr(11), Shift+Enter), and
what people porting scripts try first, so text_param now reads it as
U+2028, the forced line break, next to the CR handling it already has.
script --help and docs/agents.md say so.

docs/agents.md

@@ -26,7 +26,7 @@ of step N's result: N is the 0-based step index (comments and blank lines are no
 step) and the path goes through result fields and array indices (`"$1.story"`, `"$3.ids.0"`); `"${N.path}"`
 interpolates inside longer strings. Any other string starting with `$` stays as written (`"$1-$2"`, `"$5 off"`), and
 `$$` writes a literal `$` anywhere (`"$$1"` passes `$1`, a GREP group). In text parameters `\n` starts a new paragraph and `\u2028` is a forced line
-break. Most commands ignore parameters they don't know instead of rejecting them, so check names with `describe`.
+break (`\u000b`, Word's line break, is read as one too). Most commands ignore parameters they don't know instead of rejecting them, so check names with `describe`.
 `designcraft-cli script --help` prints this reference.
 
 ```sh