perf(frontend): keep the changelog out of the eager App chunk (C-3.19)

App.tsx imported CURRENT_VERSION from releaseNotes, which pulled its ~900-line
changelog into the eager App chunk and defeated the lazy ReleaseNotes split. App now
uses FRONTEND_VERSION (the built VITE_APP_VERSION, equal to RELEASE_NOTES[0].version
by release convention) from lib/version, and CURRENT_VERSION is removed. Verified in
the built bundle: the changelog text now lives only in the ReleaseNotes lazy chunk.

frontend/src/App.tsx

@@ -35,7 +35,10 @@ import ErrorDialog from "./components/ErrorDialog";
 import VersionBanner from "./components/VersionBanner";
 import DemoBanner from "./components/DemoBanner";
 import { focusAccessRequestsTab } from "./lib/adminUsersTab";
-import { CURRENT_VERSION } from "./lib/releaseNotes";
+// The built app version, NOT imported from releaseNotes — importing anything from that module
+// pulls its whole ~900-line changelog into the eager App chunk and defeats the lazy ReleaseNotes
+// split. FRONTEND_VERSION equals RELEASE_NOTES[0].version by release convention (both bump together).
+import { FRONTEND_VERSION } from "./lib/version";
 
 // The page modules (and their side rails) are code-split per route via the module registry
 // (components/moduleRegistry). App keeps only the persistent-shell chunks + the channel page and the
@@ -389,7 +392,7 @@ export default function App() {
             banners={
               <>
                 {meQuery.data!.is_demo && <DemoBanner />}
-                <VersionBanner onOpen={() => openReleaseNotes(CURRENT_VERSION)} />
+                <VersionBanner onOpen={() => openReleaseNotes(FRONTEND_VERSION)} />
               </>
             }
           >

frontend/src/lib/releaseNotes.ts

@@ -923,5 +923,3 @@ export const RELEASE_NOTES: ReleaseEntry[] = [
     ],
   },
 ];
-
-export const CURRENT_VERSION = RELEASE_NOTES[0]?.version ?? "dev";