fix(app): drop blocking version-handshake; Shutdown is fire-and-forget

The handshake ran synchronously in Bridge::connect: on a build-id mismatch it
sent Cmd::Shutdown and awaited a reply that never flushes (the daemon exits
first), so request() hit its 5s timeout and the reconnect-retry respawned the
daemon and re-sent Shutdown — a loop that produced repeated 'spaceshd
listening' lines and a multi-second launch delay. The id stamps also differed
between the separately-built daemon and GUI, so it fired on normal launches.

- Remove the handshake auto-restart; `make install`/`reinstall` already kill
  and replace the daemon reliably. health.build stays for display in Settings.
- Shutdown now goes through a fire-and-forget send (no reply wait, no retry),
  fixing the same loop for the Settings Restart button.
- Makefile: `make app-bundle` builds just the .app via `tauri build --bundles
  app` (no .dmg, no hdiutil) and `reinstall` uses it — faster self-update that
  can't hang on a mounted DMG volume.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Makefile

@@ -44,14 +44,18 @@ targets: ## add rust targets for the universal build
 
 .PHONY: dmg
 dmg: targets ## build the universal (Intel + Apple Silicon) .dmg — UNSIGNED
-	# Tauri's universal build compiles each arch separately and expects a sidecar
-	# named with THAT arch's triple; it lipo's them into the universal bundle and
-	# ships spaceshd inside spacesh.app/Contents/MacOS (else the GUI is offline).
+	# Tauri's universal build needs BOTH the per-arch sidecars (resolved during each
+	# arch sub-build) AND a fat spaceshd-universal-apple-darwin (copied into the final
+	# bundle — Tauri does not lipo sidecars itself). spaceshd ships inside
+	# spacesh.app/Contents/MacOS else the GUI is offline.
 	cargo build --release -p spaceshd --target aarch64-apple-darwin
 	cargo build --release -p spaceshd --target x86_64-apple-darwin
 	rm -rf $(SIDECAR_DIR) && mkdir -p $(SIDECAR_DIR)   # avoid stale sidecars poisoning the bundle
 	cp target/aarch64-apple-darwin/release/spaceshd $(SIDECAR_DIR)/spaceshd-aarch64-apple-darwin
 	cp target/x86_64-apple-darwin/release/spaceshd  $(SIDECAR_DIR)/spaceshd-x86_64-apple-darwin
+	lipo -create -output $(SIDECAR_DIR)/spaceshd-universal-apple-darwin \
+		target/aarch64-apple-darwin/release/spaceshd \
+		target/x86_64-apple-darwin/release/spaceshd
 	cd $(APP_DIR) && npm run tauri build -- --target $(TAURI_TARGET) --config $(BUNDLE_CONFIG)
 	@echo "→ $(DMG_DIR)" && ls -lh $(DMG_DIR)/*.dmg
 
@@ -63,6 +67,13 @@ dmg-native: ## build a .dmg for the current arch only (faster)
 	cd $(APP_DIR) && npm run tauri build -- --config $(BUNDLE_CONFIG)
 	@ls -lh $(NATIVE_DMG_DIR)/*.dmg
 
+.PHONY: app-bundle
+app-bundle: ## build just the native .app (no .dmg/hdiutil — fast, for self-install)
+	cargo build --release -p spaceshd
+	rm -rf $(SIDECAR_DIR) && mkdir -p $(SIDECAR_DIR)
+	cp target/release/spaceshd $(SIDECAR_DIR)/spaceshd-$(NATIVE_TRIPLE)
+	cd $(APP_DIR) && npm run tauri build -- --bundles app --config $(BUNDLE_CONFIG)
+
 .PHONY: dev
 dev: ## run the app in dev mode (tauri dev)
 	cd $(APP_DIR) && npm run tauri dev
@@ -90,7 +101,7 @@ install-universal: kill-daemon ## install the universal .app to /Applications
 	xattr -dr com.apple.quarantine /Applications/spacesh.app
 
 .PHONY: reinstall
-reinstall: dmg-native install ## native rebuild + reinstall + restart daemon (fast self-update)
+reinstall: app-bundle install ## fast self-update: build .app (no dmg), reinstall, restart daemon
 
 # ---- Tests ----