Add bunny.net edge script + deploy workflow (geo-pricing, deployable half)

[taobojlen]

Test plan, merge order below. This PR is the deployable half of geo-localized pricing — the edge script + its deploy workflow — split out so it can be merged to main and dispatched for testing before the website changes land.

What

The bunny.net middleware edge script that rewrites the displayed price based on the visitor's country (CDN-RequestCountryCode), plus the manual GitHub workflow to deploy it.

Visitor	Price shown
UK (GB, GG, JE, IM)	£25/year (static default, untouched)
Everywhere else	$35/year (edge script rewrites data-price elements)

Why split from #10

Manual workflows (workflow_dispatch) only run from main. To test the edge script end-to-end (deploy it → attach to staging pull zone → verify the rewrite), the workflow file needs to be on main first. Same pattern that worked for the staging site deploy.

Safe to merge independently

The script only rewrites elements with data-price="" attributes. Those attributes don't exist on the site yet (they arrive in the companion website PR #10). Until then, the script is a no-op on every page — it runs, finds nothing to rewrite, passes the response through. Merging this first carries no risk.

Files

Edge script (edge-script/):

• src/pricing.ts — middleware: reads cdn-requestcountrycode, rewrites [data-price] for non-UK via HTMLRewriter
• src/main.ts — entry point
• src/bunny-globals.d.ts — ambient types for HTMLRewriter (bunny runtime global)
• build.mjs + deno.json — esbuild bundle to single dist/index.ts
• README.md — full setup/deploy/verify docs

Deploy:

• .github/workflows/deploy-edge-script.yml — manual-dispatch: type-check + bundle + upload (secrets: BUNNY_STAGING_SCRIPT_ID, BUNNY_STAGING_DEPLOY_KEY)

Verified

• deno check src/main.ts ✅
• deno task build ✅
• zizmor ✅ (no findings)

Test plan (merge order)

1. Merge this PR → deploy-edge-script.yml lands on main.
2. Create the middleware edge script in the bunny dashboard + attach to the staging pull zone (see edge-script/README.md).
3. Add secrets BUNNY_STAGING_SCRIPT_ID + BUNNY_STAGING_DEPLOY_KEY.
4. Run "Deploy edge script (staging)" workflow (dispatch against main).
5. Verify the script is live on staging (bunny dashboard → Script → Logs, or check for the middleware processing requests).
6. Then merge Add geo-localized pricing via bunny.net edge script #10 (website data-price markers) + re-deploy the staging site → full geo-pricing test.