Fix: Add traefik.docker.network label to prevent routing to wrong network

[dlaporte]

Changes

When a Docker Compose app has multiple networks (e.g., an internal: true
network for service isolation), Traefik randomly picks which network IP to
route to because Go map iteration is non-deterministic. If it picks an
unreachable network, requests hang.

fqdnLabelsForCaddy() already handles this by emitting caddy_ingress_network,
but fqdnLabelsForTraefik() never emitted the equivalent traefik.docker.network
label. This PR adds it, following the same pattern: use $uuid for Docker
Compose deployments (where $serviceLabels is set), and $network for
single-container apps.

Three files changed:

• bootstrap/helpers/docker.php — added ?string $network = null parameter
  and label emission to fqdnLabelsForTraefik()
• bootstrap/helpers/parsers.php — pass $network to all 4 call sites
• bootstrap/helpers/shared.php — pass $resource->destination->network to
  all 4 call sites

Issues

• Fixes [Bug]: coolify-proxy loses connectivity to app container on custom Docker networks (504 timeout) #6215

Category

• Bug fix
• Improvement
• New feature
• Adding new one click service
• Fixing or updating existing one click service

Preview

N/A — label-only change with no UI impact.

AI Assistance

• AI was NOT used to create this PR
• AI was used (please describe below)

If AI was used:

• Tools used: Claude Code
• How extensively: AI identified the relevant code paths and generated the
  initial diff. All changes were reviewed and verified by a human against
  the existing Caddy implementation to ensure correctness.

Testing

• Reproduced the issue on a Coolify v4.0.0-beta.468 instance with a Docker
  Compose app using an internal: true sandbox network alongside the
  Coolify-managed network
• Confirmed Traefik non-deterministically routes to the internal network IP,
  causing request hangs
• Verified the fix mirrors the existing fqdnLabelsForCaddy() logic exactly
• The new parameter defaults to null and the label is only emitted when a
  network value is provided, so existing single-network deployments are unaffected

Contributor Agreement

• I have read and understood the contributor guidelines. If I have failed to follow any guideline, I understand that this PR may be closed without review.
• I have searched existing issues and pull requests (including closed ones) to ensure this isn't a duplicate.
• I have tested all the changes thoroughly with a local development instance of Coolify and I am confident that they will work as expected when a maintainer tests them.