feat: Electron desktop app, native ffmpeg export, fully static web

- apps/desktop: Electron shell serving the static web build over a
  privileged opencut:// protocol; exports stream frames over IPC to a
  bundled ffmpeg (libx264/libvpx-vp9, BT.709 tagged) with backpressure.
  electron-builder packaging: AppImage, deb, rpm.
- apps/web: dead backend deleted (better-auth, drizzle/pg, upstash,
  botid, freesound proxy, blog, rss, env validation); next build emits
  a zero-env static export; /editor/[project_id] -> /editor?project=.
- Native exporter mirrors SceneExporter; activates when the preload
  bridge is present; web keeps the mediabunny path.
- Docker self-hosting now builds and serves the static export via nginx.
- Release workflow: v* tags publish static web tarball + Linux packages.
- Changelog 0.4.0; README/AGENTS/CONTRIBUTING/roadmap updated.
- GPUI/Rust rewrite parked on branch rust-rewrite.

1 files changed, 22 insertions, 0 deletions

diff --git a/apps/desktop/src/preload.ts b/apps/desktop/src/preload.ts
new file mode 100644
index 00000000..ad3f6cf9
--- /dev/null
+++ b/apps/desktop/src/preload.ts
@@ -0,0 +1,22 @@
+import { contextBridge, ipcRenderer } from "electron";
+import type { DesktopExportBegin } from "./export.js";
+
+const api = {
+	isDesktop: true as const,
+	exportBegin: (
+		opts: DesktopExportBegin,
+	): Promise<{ id: string; filePath: string } | null> =>
+		ipcRenderer.invoke("export:begin", opts),
+	exportWriteAudio: (id: string, pcm: ArrayBuffer): Promise<void> =>
+		ipcRenderer.invoke("export:writeAudio", id, pcm),
+	exportWriteFrame: (id: string, rgba: ArrayBuffer): Promise<void> =>
+		ipcRenderer.invoke("export:writeFrame", id, rgba),
+	exportFinish: (id: string): Promise<void> =>
+		ipcRenderer.invoke("export:finish", id),
+	exportCancel: (id: string): Promise<void> =>
+		ipcRenderer.invoke("export:cancel", id),
+	revealFile: (path: string): Promise<void> =>
+		ipcRenderer.invoke("reveal-file", path),
+};
+
+contextBridge.exposeInMainWorld("opencutDesktop", api);