Fix black window on Linux + NVIDIA (WebKitGTK DMABUF renderer)

On the NVIDIA proprietary driver the app booted, logged "miniSCP started",
reported no error — and painted a completely black window, with stderr showing
"Failed to create GBM buffer of size WxH: Invalid argument" and an X11
GLXBadWindow. WebKitGTK's DMABUF renderer cannot allocate buffers there;
WEBKIT_DISABLE_DMABUF_RENDERER=1 is the upstream workaround. Pre-existing on
Linux, unrelated to the context-menu change — it just had never been looked at
because nothing on Linux had been run before.

The app CANNOT apply this to itself. WebKit reads the variable when it forks
its web process, and Bun's `process.env` writes do not propagate to child
processes (verified: a spawned child sees it unset), so setting it in
src/bun/index.ts is inert even from a module imported before `electrobun/bun`.
It has to be in the environment before the app process starts, which means
every launch path must inject it:

- scripts/linux-gpu.ts — shared `launchEnv()` helper, gated on
  /proc/driver/nvidia so Intel/AMD keep hardware compositing, and never
  overriding an explicit value from the user's environment.
- scripts/dev.ts — uses it for `bun run dev`.
- scripts/start.ts (new) — `bun run start` previously called `bunx electrobun
  dev` straight from package.json, where no env could be set; it now goes
  through a script like dev does.
- scripts/release.ts — writes a `miniSCP.sh` wrapper beside bin/launcher in the
  Linux tarball, since a packaged app goes through none of the above.

Documented in gotchas.md (including that a "does it boot?" log check does NOT
catch this — the log looks healthy) and platform-notes.md, with the smoke test
updated to require that the UI actually renders.

Verified: backend `tsc --noEmit` clean, `bun run build:ui` clean, and
`bun run start` now boots with zero GBM/GLX errors.

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

scripts/release.ts

@@ -6,7 +6,7 @@
 // an arm64 Mac: we fetch electrobun's x64 CLI binary and run it under
 // Rosetta 2 — it sees an x64 host, pulls the x64 core, and packages mac-x64.
 // Artifacts land in release/<target>/miniSCP-Build<N>-<target>.<ext>.
-import { cpSync, existsSync, mkdirSync, readdirSync } from "node:fs";
+import { cpSync, existsSync, mkdirSync, readdirSync, writeFileSync } from "node:fs";
 import os from "node:os";
 import path from "node:path";
 
@@ -131,6 +131,24 @@ if (requested === "win-x64" || requested === "linux-x64") {
 			run(["powershell", "-Command", `Compress-Archive -Force -Path '${appDir}\\*' -DestinationPath '${portable}'`]);
 			out.push(path.basename(portable));
 		} else {
+			// Ship a wrapper beside the launcher: the packaged app never goes
+			// through scripts/start.ts, and the NVIDIA/DMABUF workaround has to be
+			// in the environment BEFORE the process starts (see scripts/linux-gpu.ts).
+			const wrapper = path.join(appDir, `${BRANDING.appName}.sh`);
+			writeFileSync(
+				wrapper,
+				[
+					"#!/bin/sh",
+					"# WebKitGTK's DMABUF renderer cannot allocate GBM buffers on the NVIDIA",
+					"# proprietary driver — the window renders black. Disable it there only.",
+					'if [ -z "$WEBKIT_DISABLE_DMABUF_RENDERER" ] && [ -e /proc/driver/nvidia ]; then',
+					"  export WEBKIT_DISABLE_DMABUF_RENDERER=1",
+					"fi",
+					'exec "$(dirname "$(readlink -f "$0")")/bin/launcher" "$@"',
+					"",
+				].join("\n"),
+				{ mode: 0o755 },
+			);
 			const tarball = path.join(outDir, `${BRANDING.appName}-${buildName}-linux-x64.tar.gz`);
 			// -C the parent so the archive unpacks into one named folder
 			run(["tar", "-czf", tarball, "-C", path.dirname(appDir), path.basename(appDir)]);