Closes#246. The transcript, composer and approval controls move from
structured.ts/structuredRender.ts into components under
web/src/components/structured/, against docs/STRUCTURED-VIEW.md: eight row
kinds, both projections, the single-active approval nonce, and diff rendering
with its own line counts.
The pure layers stay shared — structuredDiff.ts computes the diff,
structuredRender.ts still sanitizes markdown — and model.ts holds the
client-side decisions (activity grouping, notice classification, offered
decisions, `/` completion) so they are testable without a DOM.
Like TerminalPane, the pane draws the body only; pane chrome reads the
connection through onStatusChange.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>