build: pass -tags desktop,production to go build (Wails requirement)

Without these tags Wails aborts at startup with a "Wails applications
will not build without the correct build tags" MessageBox. Local
rebuild.sh, the cross-compile step in release.yml, and the windows
build step in build.yml all needed the flag — only the local Wails
dev wrapper was already passing it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

rebuild.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -e
+cd "$(dirname "$0")"
+echo "[$(date +%H:%M:%S)] frontend..."
+(cd internal/gui/frontend && npm run build 2>&1 | tail -3)
+echo "[$(date +%H:%M:%S)] go build..."
+CGO_ENABLED=0 go build -trimpath -tags "desktop,production" \
+  -ldflags "-s -w -H=windowsgui -X main.Version=99.99.99-test" \
+  -o drover-test.exe ./cmd/drover
+echo "[$(date +%H:%M:%S)] OK $(stat -c %s drover-test.exe) bytes"