Mirrors the data-driven pattern PR #2454 set in ConfigTab: read
runtime_config.providers from /templates and filter the modal's
provider <select> to that subset. Same source of truth, three fewer
hardcoded copies of the provider list.
Behavior:
- Template declares providers → dropdown shows only those.
- Template ships no providers field → fall back to full HERMES_PROVIDERS
catalog (back-compat for older templates / self-hosted setups).
- Declared list has no overlap with our static metadata → fall back to
full catalog so the form can't lock the operator out.
- hermesProvider snaps back to the first available pick when its
current value falls out of the filtered list.
Tests: 3 new pinning the filter, no-providers-field fallback, and
the unknown-providers fallback. All 27 CreateWorkspaceDialog tests
pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
e1496936e9