docs(security): address second round of review feedback

- SECURITY.md: add Supported Versions table; reword SLA paragraph as
  a bullet list per reviewer suggestion
- bug_report.yml: render reproduction textarea as shell so commands and
  JSON get syntax highlighting, matching the logs field
- question.yml: add transport and install_method dropdowns mirroring
  bug_report.yml so setup questions capture the same context

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

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -31,6 +31,7 @@ body:
         1. Call `nc_contacts_create` with `full_name`, `email`, `phone`
         2. Inspect the contact in the Nextcloud web UI
         3. Only the name is present
+      render: shell
     validations:
       required: true