feat: add Healthchecks template

[tizianozonta]

What is this PR about?

New PR of Healthchecks

Adds a template for Healthchecks, an open-source cron job and background task monitoring service.

• healthchecks/healthchecks:v4.4 (official image) + postgres:16-alpine, app waits for DB via service_healthy
• Migrations, sendalerts and sendreports run automatically inside the app container (upstream uwsgi.ini)
• SECRET_KEY and DB password generated with helpers; SITE_ROOT, ALLOWED_HOSTS and PING_ENDPOINT derived from the domain
• DEBUG=False set explicitly (upstream defaults to True)
• Registration closed by default (REGISTRATION_OPEN=False); create the first admin with ./manage.py createsuperuser from the container terminal
• SMTP variables included with empty placeholders (fill in to enable email alerts / magic-link login)
• Inbound email pings (SMTPD_PORT) intentionally not enabled, since it would require a published port

Checklist

Before submitting this PR, please make sure that:

• I have read the suggestions in the README.md file https://github.com/Dokploy/templates?tab=readme-ov-file#general-requirements-when-creating-a-template
• I have tested the template in my instance, so the maintainers don't spend time trying to figure out what's wrong.
• I have added tests that demonstrate that my correction works or that my new feature works.

node build-scripts/generate-meta.js --check passes. Stack smoke-tested locally with docker compose (migrations applied, uWSGI up, login page returns 200). Tested on a Dokploy instance via the preview base64: deploy OK, admin created with createsuperuser, login works behind Traefik.

Issues related (if applicable)

Screenshots or Videos

[github-actions]

built with Refined Cloudflare Pages Action

⚡ Cloudflare Pages Deployment

Name	Status	Preview	Last Commit
templates	✅ Ready (View Log)	Visit Preview	50da81b