feat(rhema-code): add the colors setting with four palettes

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.

web/claw/app/components/StatusDot.vue

@@ -0,0 +1,34 @@
+<script setup lang="ts">
+// One small round state dot with an honest tone: ok, warn, error, or
+// idle gray. The only place status color lives at a glance.
+defineProps<{
+  tone: 'ok' | 'warn' | 'error' | 'idle'
+}>()
+</script>
+
+<template>
+  <span class="dot" :class="tone" aria-hidden="true" />
+</template>
+
+<style scoped>
+.dot {
+  display: inline-block;
+  flex: none;
+  width: 8px;
+  height: 8px;
+  border-radius: 50%;
+  background: var(--text3);
+}
+
+.dot.ok {
+  background: var(--ok);
+}
+
+.dot.warn {
+  background: var(--warn);
+}
+
+.dot.error {
+  background: var(--error);
+}
+</style>