feat: add drupal-contrib template with beta unified issue picker, fixes #59

[rfay]

Closes #59. Tracking issue for promoting to production: #121.

What's in this PR

New drupal-contrib Coder template — automated workspace for developing Drupal contrib modules and themes, with optional issue branch support via ddev/ddev-drupal-contrib.

• Any drupal.org project cloned to /home/coder/{project_name}/
• Drupal installed as a dev dependency via ddev poser (module/theme auto-symlinked into web root)
• Issue fork checkout via issue_fork + issue_branch parameters
• ddev phpunit, ddev phpcs, ddev phpstan available via the addon
• Mutable share_drupal_site parameter (owner/authenticated/public) on both drupal-contrib and drupal-core
• drupal-contrib/scripts/test-issue-branches.sh — local/workspace test matrix script
• .github/workflows/drupal-contrib-integration-test.yml — CI integration test

Picker changes (conservative — production picker untouched)

• docs/drupal-issue.html — restored to original core-only picker (no change to production behavior)
• docs/drupal-contrib-picker.html — new unified picker (core + contrib), defaults to staging-coder.ddev.com; BETA badge makes the staging target clear
• docs/index.html — beta card added alongside the original picker card

Manual testing

1. Template — create a contrib workspace on staging

coder --url https://staging-coder.ddev.com create \
  --template drupal-contrib my-contrib-test \
  --parameter project_name=token \
  --parameter drupal_version=11 \
  --yes

Wait for setup (~5-10 min). Then verify:

• Workspace reaches running state
• Drupal site loads (click the Drupal Site app or check port 8080)
• ddev drush pm:list --status=enabled | grep token returns a result
• VS Code opens at /home/coder/token

2. Issue fork — check out an issue branch

coder --url https://staging-coder.ddev.com create \
  --template drupal-contrib my-token-issue \
  --parameter project_name=token \
  --parameter drupal_version=11 \
  --parameter issue_fork=3568144 \
  --parameter issue_branch=3568144-fix-something \
  --yes

(Use a real issue number from drupal.org/project/token/issues — the branch name must match an actual branch on the issue fork.)

• Issue branch is checked out (git branch inside workspace)
• Module still installs and enables correctly

3. Beta picker — no PR checkout needed

Serve the picker locally from any checkout of this branch:

cd docs && python3 -m http.server 8900
# open http://localhost:8900/drupal-contrib-picker.html

• Paste a Drupal core issue URL → routes to drupal-core template on staging
• Paste a contrib issue URL (e.g. drupal.org/project/issues/3456789 for a token issue) → routes to drupal-contrib template on staging
• Paste a bare project name (token) → opens plain contrib workspace form
• ?coder=https://coder.ddev.com override works (check the workspace URL in the launched tab)

4. Test matrix script (inside a Coder workspace)

scp drupal-contrib/scripts/test-issue-branches.sh myworkspace.coder:/tmp/
ssh myworkspace.coder bash /tmp/test-issue-branches.sh

Expected: token:11, pathauto:11, token:10 all show PASS in the summary table.

5. Share parameter

On any drupal-core or drupal-contrib workspace:

• Default sharing is "owner only" (Drupal site URL not publicly accessible)
• Change parameter to "public", restart workspace → URL becomes publicly accessible

[rfay]

Testing the beta picker

The htmlpreview link in the original version of this comment does not work — htmlpreview strips <script> tags, so the picker renders but nothing executes.

The picker can be tested after this PR is merged, when GitHub Pages deploys it to:

https://start.coder.ddev.com/drupal-contrib-picker

The picker defaults to staging-coder.ddev.com. You'll need a staging account. Things to try:

• Paste a Drupal core issue URL → should route to the drupal-core template on staging
• Paste a contrib issue URL (e.g. any issue under drupal.org/project/token/issues/...) → should route to drupal-contrib template on staging
• Paste a bare project name (token, pathauto) → should show the plain dev form for contrib
• Add ?coder=https://coder.ddev.com to the URL to target production instead of staging

Issue #121 tracks the final promotion step: once validated on staging, replace drupal-issue.html with this unified picker and point it at production.