feat(canvas): mount SearchDialog in desktop + mobile canvas shells

Adds Cmd+K workspace search to both canvas entry points:
- page.tsx: mounts SearchDialog in the desktop shell
- MobileApp.tsx: mounts SearchDialog in the mobile shell

Phase 20.3: closes the "Workspace search (Cmd+K)" requirement.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

canvas/src/app/page.tsx

@@ -4,6 +4,7 @@ import { useEffect, useState } from "react";
 import { Canvas } from "@/components/Canvas";
 import { Legend } from "@/components/Legend";
 import { CommunicationOverlay } from "@/components/CommunicationOverlay";
+import { SearchDialog } from "@/components/SearchDialog";
 import { MobileApp } from "@/components/mobile/MobileApp";
 import { Spinner } from "@/components/Spinner";
 import { connectSocket, disconnectSocket } from "@/store/socket";
@@ -118,6 +119,7 @@ export default function Home() {
       <Canvas />
       <Legend />
       <CommunicationOverlay />
+      <SearchDialog />
       {hydrationError && (
         <div
           role="alert"

canvas/src/components/mobile/MobileApp.tsx

@@ -20,6 +20,7 @@ import { MobileMe } from "./MobileMe";
 import { MobileSpawn } from "./MobileSpawn";
 import { usePalette } from "./palette";
 import { MobileAccentProvider } from "./palette-context";
+import { SearchDialog } from "@/components/SearchDialog";
 
 type Route = "home" | "canvas" | "detail" | "chat" | "comms" | "me";
 
@@ -204,6 +205,8 @@ export function MobileApp() {
       {showTabBar && <TabBar dark={dark} active={activeTab} onChange={onTabChange} />}
 
       {showSpawn && <MobileSpawn dark={dark} onClose={() => setShowSpawn(false)} />}
+
+      <SearchDialog />
     </main>
     </MobileAccentProvider>
   );