v0.6.23 — /compose mobile layout hotfix (P1 from user testing)

v0.6.23 — /compose mobile layout hotfix (P1 bug)

User reported (with screenshot) that /compose becomes unusable at
viewport widths < 1024px: the sidebar's natural content height
pushed the canvas + inspector off-screen, leaving only the session
list visible.

What changed (CSS-only)

• At <1024px, .compose-grid switches from display: grid to
  display: flex; flex-direction: column; height: calc(100vh - 200px).
• Sidebar capped at 35vh (a search bar + filter + a scrollable
  items list, more on scroll).
• Canvas gets flex: 1; min-height: 0 so it fills the remaining
  space and shrinks to fit instead of overflowing.
• Inspector is unchanged (already position: fixed on mobile,
  removed from the flex flow).
• Desktop layout (≥1024px) is unchanged — original 3-column
  grid preserved.

How to verify

git pull origin main
git checkout v0.6.23
pilot dashboard
# Resize the browser window below 1024px wide
# You should see: toolbar at top, sidebar (capped), canvas (the
# bulk of the visible area), and the inspector bottom-sheet
# unchanged at the bottom

Lesson

• Unit tests + tsc + lint verify the code works, not that the user
  can see what they need to see. Headless tests don't exercise
  rendered layout.
• "Tests pass ≠ UI works." Add a smoke checklist for any
  viewport-sized page: render at 800×600, 1024×768, 1440×900 and
  verify all primary panels are visible.

Thanks to the user for the screenshot — that's the only reason this
bug got fixed.