Supabase workflow inquiry backend

This static site does not write directly to public.workflow_inquiries. The browser posts JSON to the submit-workflow-inquiry Supabase Edge Function, and the function inserts the validated payload with SUPABASE_SERVICE_ROLE_KEY.

Deploy

Apply the table migration:
```
supabase db push
```
Phase 3 adds nullable role, owning_team, volume, and cost_risk columns and extends the existing workflow-type constraint. Existing rows remain valid and no data is rewritten or removed. Deploy the migration before deploying the Phase 3 Edge Function so new fields can be inserted safely.

Deploy the Edge Function:

supabase functions deploy submit-workflow-inquiry

Confirm the function has these environment variables available:
- SUPABASE_URL
- SUPABASE_SERVICE_ROLE_KEY
Configure the public frontend endpoint for GitHub Pages. This repo is a Jekyll site, not a Vite app, but the GitHub Actions Pages workflow intentionally reads the public repository variable named VITE_WORKFLOW_INQUIRY_ENDPOINT and writes it into generated Jekyll data at build time. In the repository Pages settings, use GitHub Actions as the source, then set the repository variable to:
```
https://dgrwgiagpcqkxdokhglb.functions.supabase.co/submit-workflow-inquiry
```
The workflow form reads site.data.env.workflow_inquiry_endpoint. The committed _data/env.yml provides the public Supabase Edge Function endpoint for GitHub Pages builds; VITE_WORKFLOW_INQUIRY_ENDPOINT can still override it during the Pages build when that repository variable is set. If neither value is present, the browser shows a safe fallback message and does not attempt to submit the form.

Only put the public Edge Function URL in this frontend variable. Do not expose SUPABASE_SERVICE_ROLE_KEY, Supabase secret keys, or other server-only credentials in GitHub Pages variables or client-side code.

Response shape

Success responses use:

{
  "success": true,
  "message": "Thanks — your workflow inquiry was received. I will review it and follow up by email.",
  "inquiry_id": "..."
}

Validation or server errors use:

{
  "success": false,
  "message": "Please fix the highlighted fields and submit again.",
  "errors": [
    { "field": "email", "message": "Enter a valid work email address." }
  ]
}