Add bot-driven room app UI via im.paarrot.ui state.

Bots can publish a declarative panel UI that takes over a room; user
actions are sent as im.paarrot.ui.action timeline events.

src/app/features/room-app/RoomAppView.css.ts

@@ -0,0 +1,74 @@
+import { style } from '@vanilla-extract/css';
+import { recipe } from '@vanilla-extract/recipes';
+import { DefaultReset, config, toRem } from 'folds';
+
+export const Root = style([
+  DefaultReset,
+  {
+    display: 'flex',
+    flexDirection: 'column',
+    flexGrow: 1,
+    minHeight: 0,
+    minWidth: 0,
+  },
+]);
+
+export const Header = style({
+  paddingLeft: config.space.S200,
+  paddingRight: config.space.S200,
+});
+
+export const Body = style([
+  DefaultReset,
+  {
+    flexGrow: 1,
+    minHeight: 0,
+    overflow: 'auto',
+    padding: config.space.S400,
+  },
+]);
+
+export const Panel = style({
+  display: 'flex',
+  flexDirection: 'column',
+  gap: config.space.S300,
+  width: '100%',
+});
+
+export const Row = style({
+  display: 'flex',
+  flexDirection: 'row',
+  flexWrap: 'wrap',
+  gap: config.space.S200,
+  alignItems: 'center',
+});
+
+export const Field = style({
+  display: 'flex',
+  flexDirection: 'column',
+  gap: config.space.S100,
+  minWidth: toRem(160),
+  flexGrow: 1,
+});
+
+export const Image = style({
+  maxWidth: '100%',
+  height: 'auto',
+  borderRadius: config.radii.R300,
+});
+
+export const Spacer = recipe({
+  base: {
+    flexShrink: 0,
+  },
+  variants: {
+    size: {
+      sm: { height: config.space.S200 },
+      md: { height: config.space.S400 },
+      lg: { height: config.space.S600 },
+    },
+  },
+  defaultVariants: {
+    size: 'md',
+  },
+});