Default signups off, improve Docker deploy, fix onboarding step UI.

Show a disabled-registration state on the register page when DISABLE_SIGNUPS is true (default), document docker-deploy.sh with git-SHA image tags, and align onboarding progress circles and labels on a shared grid.

Co-authored-by: Cursor <cursoragent@cursor.com>

package.json

@@ -15,6 +15,7 @@
     "docker:up": "colima start && docker compose -f docker-compose.dev.yml up -d",
     "docker:down": "docker compose -f docker-compose.dev.yml down && colima stop",
     "docker:dev:down": "docker compose -f docker-compose.dev.yml down && colima stop",
+    "docker:deploy": "./scripts/docker-deploy.sh",
     "deploy": "drizzle-kit push && next build",
     "dev": "next dev --turbo",
     "format:check": "prettier --check \"**/*.{ts,tsx,js,jsx,mdx}\" --cache",