Upgrade to Elm Pages 3 and update depends

[katjam]

Description

Upgrade out framework & dependencies

Acceptance Criteria

• elm pages is version 3.0.x
• node is version 20
• node scripts run without error (postinstall, start, build, format, test)
• [Bug]: CI is building inconsistently #404
• site builds and deploys without error
• pages are identical to release on https://transdimension.uk

Plan first

• Upgrade other deps
• Upgrade to elm-pages v3
• move source files
• move theme and route files out to get index working in v3
• replace Path with UrlPath
• replace Cmd with Effect
• amend script/src/AddRoute.elm & AddStaticRoute to use elm-css
• Amend default mainfest in app/Api.elm ? This is new here in v3 - check where was before

Considerations

• migrate Decoders
• migrate DataSource
• amend Route exports for data and ActionData

Initial port of Theme & Routes

• About
• 404/error #443
• Events (index & single)
• Partners index
• Partner single
• Index
• Port Join Us form to elm-pages v3 #442
• News index
• News item
• Add stock images to News Item
• Add Events back into Partner_.elm pages
• Privacy
• Meta / Head
• Use cached data for Partner & Event #432

Next

• Clear out with elm-review
• Review efficiency of build and data loading in context of below list
• Update readme #444

Review issues after upgrade

Some of them might be able move to AC

• Set event import window dynamically #391
• [Bug]: Events more than a month away, not displaying #386
• Update README to discuss how to set cron timer & how Join Us send works #364
• Load all events in index - but limit single pages in static build by date range #351
• [Bug]: Event pages are taking nearly half a second to build which is making the build time out #348
• Always try to load live data #296
• Speed up build by caching event data #269
• Create auto staging deploy #268
• Add favicons #210
• Document where data comes from and how to edit #72
• Allow site to work offline as a PWA #17

[katjam]

Suggested upgrade path for v2 to v3:
https://discourse.elm-lang.org/t/introducing-elm-pages-v3-full-stack-elm-and-scripts/9185/12

elm-pages v3 docs:
https://elm-pages.com/docs/

[katjam]

removing OptimizedDecoder's and replacing with plain Decoders, and using the new BackendTask and FatalError APIs instead of DataSource

https://github.com/dillonkearns/elm-pages-v3-beta/blob/master/docs/3.0-upgrade-notes.md

[kimadactyl]

ahha i didnt see this ticket! now have a really good idea what this is taking to get done, wow its a lot!

[katjam]

This needs further work, but much improvement.

Further work:

• node test script broken [Bug]: Fix test runner #446
• build warning on time fetch [Bug]: Get rid of "No such label BackendTask" warning #449