fix: cell editor grows taller than the cell while editing (name/classification)

Editing a single-line cell (`name` / `classification`), the editor textarea sometimes grows taller than the cell, putting the cursor on an empty second line, even though no line break exists in the data. Cosmetic, no data affected.

Confirmed:

- Committed values contain no `\n` (single-line).
- Pressing Enter commits and moves to the next cell, so the value is one line; only the editor box is over-tall.
- Reproduces in incognito, so it is not a browser extension.
- Intermittent, recomputed per keystroke, which is the autoResize fingerprint.

Relation to #162: same autoResize root. #162 pinned editor width (`--cress-cell-w` plus `!important`) but left height unlocked so `mei` can grow for multi-line XML. This is that height axis surfacing on single-line columns.

Fix (must be per column): lock editor height to the cell for single-line columns only (a `--cress-cell-h` counterpart, or disable vertical autoResize there). `mei` must keep free vertical growth, so a blanket lock breaks it. The intermittent misaligned selection border is likely the same root.