Migrate to Electrobun 2.0.2 (Hutch)

Electrobun 2.x replaces the vendored CLI with Hutch: the npm package is now a
bootstrap whose exports are a throwing stub, and the SDK is projected into
.hutch/devkit. The app stays on the Bun main process — `mainProcess: "bun"` is
load-bearing, since the 2.x default (Cottontail) ignores build.bun and with it
the ssh2 externals — and the bundle now ships the pinned Bun 1.4.0.

- electrobun 2.0.2 as an exact devDependency. `electrobun prepare` takes the
  old CLI re-sign step's slot in postinstall and every dev/build/start/release
  script: tsc (root tsconfig extends the devkit's) and the Angular build
  (electrobun/view mapped into the devkit) resolve the SDK there.
- Imports move to electrobun/main. The CLI re-sign script and the v1 "three"
  type shim are gone (Hutch's binaries are validly signed).
- UI: Electroview's bunSocket is hostSocket; noImplicitReturns is off because
  the devkit's raw-TS browser SDK compiles inside the UI program.
- Updater.applyUpdate() now consults before-quit, so the transfers/unsaved
  guard's "Quit Anyway" re-runs the apply instead of quitting without it.
- 2.x applies trafficLightOffset from macOS's default button position (1.18.1
  clamped it inside the titlebar); {12, 4} centres the lights in the header.
- Releases: mac-x64 dropped (2.x publishes no macOS x64 core, so no Rosetta
  path). artifacts/ is emptied before each build and published verbatim.
  Installers lost the stable- prefix (the update feed kept it), so release.ts,
  deploy.sh and the site links follow. Linux ships Electrobun's Setup
  installer instead of the portable tarball and its miniSCP.sh wrapper.
- Docs cover all of the above, plus re-checks against 2.0.2: still no native
  modal windows; window close is now cancellable through will-close.

Verified: tsc, build:ui, a stable mac-arm64 release (dmg + the v1-compatible
stable-macos-arm64 feed) and dev launches (RPC, Settings window, traffic
lights). Windows/Linux builds and the v1 -> 2.x Windows update bridge still
need their first run on native machines.

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

scripts/linux-gpu.ts

@@ -7,9 +7,10 @@
 // It has to be in the environment BEFORE the app process starts: WebKit reads
 // it when it forks its web process, and Bun's `process.env` writes do NOT
 // propagate to children (verified — a child sees the variable unset), so the
-// app cannot set this for itself from inside src/bun/. Every launch path has to
-// inject it: the dev scripts here, and the wrapper script that release.ts ships
-// beside the packaged launcher.
+// app cannot set this for itself from inside src/bun/. Only the dev launch
+// paths (`bun run dev` / `bun run start`) inject it; an installed build (the
+// official Linux Setup installer) needs the user to set
+// WEBKIT_DISABLE_DMABUF_RENDERER=1 themselves on NVIDIA.
 //
 // Scoped to NVIDIA so Intel/AMD keep hardware compositing, and an explicit
 // value from the user's environment always wins.