Fold thinking deltas into the turn's stream-ordered entries as a
thinking entry, merged back-to-back the way the stream delivers
them, instead of one flat string rendered above every call. Each
thinking block now sits where it streamed — between the calls it
precedes. Live turns keep their thinking expanded; finished turns
render it collapsed.
The stored `colors` key names a palette — rhema (the default,
Jadeite), aquamarine, black-and-white, or dracula — and the
Appearance page of /settings cycles it live, like the theme and
icon toggles beside it. Each palette carries a dark and a light
appearance under the existing `theme` key; dracula's light side is
derived, the official palette ships only dark.
The appearance decision moves off token comparison: Theme now
answers is_dark() from the ground/text luminance, so palettes
beyond the original two get the right per-profile fallback tones.
vhaudiquet