Adds the `[ERR]` / `[WRN]` validity indicator to the input
row. `App` gains `input_indicator: Option<Severity>` (the
runtime owns its timing — step E) and a pure
`input_validity_verdict()` query that runs `input_verdict`
in simple mode only (advanced mode is raw SQL, ADR-0027 §7).
`render_input_panel` reserves the rightmost six columns of
the input row unconditionally (ADR-0027 §4) — a five-column
label plus a one-column gap — so the typed command never
shifts sideways when the indicator appears or hides. The
label renders only when `input_indicator` is set: `[ERR]` in
`theme.error`, `[WRN]` in the new amber `theme.warning`
(defined for both light and dark themes).
The indicator is not yet wired live — `input_indicator`
stays `None` until the debounce lands (step E). Covered by a
render test and the theme contrast test; the input-panel
snapshot is updated for the six-column reservation.
claude@clouddev1
1a9d950cc2