[1.4] Fix mavlink endpoints page in mobile and access via proxy

[patrickelectric]

Fix mavlink endpoints page layout on mobile and proxy redirects.
Cherry-pick of #4401
Fix #4398
Helps #4399

[github-actions]

Automated PR Review

0. Summary

• Verdict: MINOR SUGGESTIONS ✏️

Cherry-pick of #4401 into 1.4-dev. EndpointCard.vue and EndpointManager.vue swap inline style="" / hard-coded utility widths for scoped CSS classes and add a @media (max-width: 600px) block so the MAVLink endpoints page wraps cleanly on mobile. vite.config.js adds changeOrigin: true + autoRewrite: true to the /ardupilot-manager dev proxy so redirects returned by that service resolve back to the proxy host — matching the "access via proxy" symptom in the title.

6. Code Quality & Style

• 6.1 [nit] core/frontend/src/components/autopilot/EndpointCard.vue:14 and :37 — the leftover min-width="106px" and width="62px" attributes on <div> elements are not valid HTML attributes (they only work on <img>, <table>, <td>, etc.), so they render as no-op custom attributes. Since this PR is already rewriting the layout of these two divs, it would be a good moment to drop them. Add the equivalent min-width / width to the .endpoint-details / .endpoint-flags scoped rules if the sizing is actually desired.
• 6.2 [nit] core/frontend/src/components/autopilot/EndpointCard.vue:38 — the desktop rule removes the flex-column utility class from the template and re-adds flex-direction: column in the .endpoint-flags scoped rule. Functionally identical, but it's a bit odd to drop a utility class only to reintroduce its behavior in CSS one line later. Keeping flex-column in the template (and only overriding it in the @media block via .endpoint-flags { flex-direction: row; }) would be a smaller diff and read more consistently with the neighbouring components.

8. Documentation

• 8.1 [nit] core/frontend/vite.config.js:246 — /ardupilot-manager is now the only proxy entry with changeOrigin / autoRewrite; everything else in the block relies on defaults. A one-line comment noting why (ardupilot-manager returns 3xx redirects whose Location header must be rewritten so the browser stays on the dev-server host) would save the next reader a trip to the http-proxy docs, and would make it obvious whether the same treatment should be extended to other services later.

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