feat(maestro): wire React app as sole web entry point

Deletes the vanilla shell and mounts App.tsx on #root. main.ts and the
23 views it drove are gone; App.tsx composes the ported components —
sidebar, multi-view, command bar, spawn modal, help and restart
overlays, daemon link, drawer — around the catalog and layout stores.

The pure parts of four deleted modules moved next to the components
that still use them: the spawn-form model and spawnSimilar into
components/spawn, the transcript's markdown/format helpers and the diff
into components/structured, the help overlay's grouping into
components/dialogs. Document-level event names now live in uiEvents.ts.

Deduplicated two pairs the migration left side by side: the sidebar
uses dialogs/KillDialog and common/ContextMenu. It also listens for the
command bar's kill/rename events, which nothing had picked up since
catalog.ts went away.

styles.css stays as the token and base layer, with `#app` renamed to
`#root` and the pane-body rules re-keyed off the classes the React
panes actually carry.

Closes #253

web/src/components/terminal/KeyBar.tsx

@@ -92,7 +92,7 @@ export function KeyBar({ armed, onToggleMod, onClearMods, onSend }: KeyBarProps)
     <div
       role="toolbar"
       aria-label="Special keys"
-      className="flex flex-wrap gap-1 border-t border-white/10 bg-black/20 p-1"
+      className="keybar-touch flex-wrap gap-1 border-t border-white/10 bg-black/20 p-1"
     >
       {KEY_DEFS.map((def) => {
         if ("mod" in def) {

web/src/components/terminal/TerminalPane.tsx

@@ -347,7 +347,11 @@ export const TerminalPane = forwardRef<TerminalPaneHandle, TerminalPaneProps>(
 
     return (
       <div className={className ? `flex h-full flex-col ${className}` : "flex h-full flex-col"}>
-        <div ref={bodyRef} className="min-h-0 flex-1" />
+        {/* `attach-body` is what styles.css keys the terminal's own sizing on
+            (`.attach-body .xterm { width/height: 100% }`) plus the hidden
+            scrollbar and touch-scroll rules. Without it the terminal measures
+            its own stale viewport and never grows back to the pane. */}
+        <div ref={bodyRef} className="attach-body min-h-0 flex-1" />
         {keybarActive && (
           <KeyBar
             armed={keyBar.armed}