treat lines ending with unquoted `|` or `&` as continued
conditions in `do` block headers so nested blocks parse correctly
across line breaks.
update `on` condition splitting to avoid breaking on newlines that
follow an unescaped trailing pipe, while still respecting quotes,
escapes, and bracket nesting.
add coverage for multiline `|`/`&` continuations in `do` parsing,
`splitAnd`, `parseOn`, and HTTP flow nested block behavior.
a0adc51269