[LHagfoss]

/remote was capped at 18 terminal rows, while its pairing QR alone needs about 29. The Remote command panel now occupies the entire terminal viewport, including the composer/footer space, and uses the same full-screen geometry for mouse selection. Other command panels retain their bounded layout.

Pairing details come first: the manual address and code are above the QR, with session status and loopback guidance below. Explicit black-on-white QR colours survive the final panel render. Closing the panel restores the composer and draft. A hidden activity-indicator hold is cleared so opening Remote between turns cannot leave the renderer continually scheduling frames.

Fixes #1918

Validation:

• cargo fmt --all -- --check
• cargo check --workspace --tests
• RUST_TEST_THREADS=4 cargo test --workspace
• scripts/check-frontend-seam.sh and git diff --check
• Render regressions cover full-height geometry, scrolling, draft/composer restoration, every QR cell and its colours in light/dark themes, and stale indicator cleanup.
• Real 80×40 pseudo-terminal, isolated config/gateway: /remote starts the gateway, registers the session, shows the manual address/code and the complete coloured QR, and closes normally. The existing user gateway/config were untouched.

The first workspace run timed out in the existing a_remote_cancel_stops_only_the_turn_it_names test; it passed in isolation and the final workspace run passed with reduced concurrency. Initial Linux CI received owner_exited instead of sharing_disabled in the existing gateway end-to-end test; that intermittent close-reason defect is tracked in #1920. The unchanged test passed on baseline main, and the complete Linux job passed on retry. All CI checks passed. Camera scanning and real iPhone connectivity were not tested.