v0.5.4

$(cat <<'EOF'

What's Changed

• Restores the framed TUI shell and outer gutter while keeping full-width chat.
• Improves dark-mode readability by replacing low-contrast secondary text with theme-aware colors.
• Fixes inline slash picker Enter handling for commands such as /m and /theme.
• Updates workspace version, lockfile, README files, and GitHub Pages source docs for v0.5.4.

Verification

• cargo check --workspace
  'EOF'
  )