Modernise repo config/setup/deps

[erikhuizinga]

Summary

• Modernise the build/toolchain for 2026: upgrade Gradle wrapper, Kotlin/JS (KMP), coroutines, Ktor, and JDK 21 runtime for docs.
• Improve docs workflow: offline bundling, local /docs proxy for dev, more robust template parsing for updated Kotlin docs markup.
• Harden app/runtime behaviour: gate external analytics scripts, address deprecated APIs/warnings, update menu/search casing and coroutines scope usage.
• Centralise versions in gradle/libs.versions.toml to keep Kotlin/coroutines/Ktor/logback/jsoup/JVM versions in a single source of truth.

[rougsig]

Does the newer version of Kotlin have new operators for Flow? Or has the behavior of Flow changed?

[erikhuizinga]

I am also preparing a PR against this one that tries to add some more marble diagrams. This is just the basis for that. If you look at the KotlinX Coroutines releases page and search for flow, you'll see some new operators have been introduced since v1.6.0 (flowmarbles uses that currently) that could be added. And I have some more ideas.

[erikhuizinga]

Here is the PR against this one: erikhuizinga#1
Note that it's in my fork of this repo, because GitHub won't allow PRs against PRs in a different repo.
I could also just push the changes to the current PR's branch, if you prefer to have it all in one place.

Feel free to review however you like, or just ignore. Also, feel free to make changes. I know the implementation isn't perfect and can be improved in a few places. Also, the menu is getting quite long, so a different UI component/behaviour might be necessary. The marble diagrams could use some throwable indicator, e.g. for the retry operator (that also needs better text). Etc. etc. etc.

I also can't promise I'll have time to fix issues / review comments, which is why I'm pushing both these branches in a reviewable but possibly still unacceptable state: I'd love for others to iterate on it. Maybe you, if you're interested?