feat: 503 and 504 outage pages

[joshlarson]

Scope

Note

I'm not entirely sure that this is the right way to version this, since these pages won't actually be served from a running Dotcom instance. I figure this is as good a place as any to stash them and iterate on them though 🤷

Asana Ticket: 📈 🛠️ [#3378] Implement custom error pages for MBTA.com when app is down

Implementation

Note

🤖 I used Copilot to build the first draft of this, and then iterated on it both with further AI prompts and by hand. Each commit whose prefix includes (robot) was generated by AI - the others were hand-written by yours truly.

Screenshots

How to test

Open the files. The buses blink!

[jlucytan]

If this is just meant to be an archive of the current state of the pages, perhaps we can keep this as a draft branch to be used for reference for perpetuity? Although the visibility isn't the greatest, so I'm not opposed to merging it in either, but I think it's a bit confusing to have the pages there while they're not being served, and future devs will just have to know that updating them does nothing.

[joshlarson]

[...] I think it's a bit confusing to have the pages there while they're not being served, and future devs will just have to know that updating them does nothing.

Yeah that's a good point. I wonder if we should put them in a clearer place, alongside a README that explains what they're for and how they actually get "deployed" (which .. uh... currently I don't even know)