mara (#3877): issue report too narrow — the 8-column table was
clipped by .shell-body's 60em readable-line-length cap, which is right
for the rest of the UI's cards/forms but too tight for a wide table.
damocles diagnosed the root cause and scoped the shape (route
allowlist + an additive .shell-body-wide modifier, no prop plumbing
through App.tsx) before asking for a nod; mara then routed the actual
build to me. Implemented that shape as scoped: /issues opts into a
90em cap via WIDE_BODY_ROUTES, every other route keeps 60em untouched.
Verified with real headless-chromium screenshots at 1280px: the issue
report's full 8-column row (through 'transitively blocks') now fits
with no horizontal scroll, and a second screenshot of /agents confirms
every other route is unaffected.