docs: update ROADMAP for wide-char/paste/OSC52/DECRQM work
Move the now-implemented items (wide/zero-width rune width, clipboard
paste + bracketed paste, OSC 52 clipboard write, DECRQM/DECRPM +
kitty-keyboard-query replies) from Later into v1 (done), and note the
residual gaps each left behind (combining marks still dropped, primary
selection and the OSC 52 query form still unsupported, kitty protocol's
actual key encoding still missing) in Later/Known v1 limitations.