The popup offered [[feature]]/[[milestone]] on every fresh line — right
under the last property or straight after a header. Only volunteer them
once there's a blank line above (the "two new lines" convention); typing
a bare `[` still summons them anywhere. Property keys are unchanged.
The pattern's trailing optional quote let a complete `status = "x"`
match, so the popup reopened after the closing quote. Drop it so the
match ends with the value, while still typing remains supported.
The TOML editor offered nothing when typing a date, leaving the
yyyy-mm-dd format undiscoverable until a parse error. Suggest today
(a full, easy-to-edit date) and the current-year prefix on empty
date values and fresh reestimates elements, backing off once a date
is being typed.
Given a source and caret offset, suggest block headers, the keys valid
for the current block (excluding ones already written), status enum
values, and the feature names referenced by a milestone's requires.
Mirrors the schema in parse.ts.
