[ui] [js] Upgrade to, and evaluate Typescript 7

[cephalization]

Typescript 7 should speed up CI dramatically, less so in app/ but especially in js/.

https://devblogs.microsoft.com/typescript/progress-on-typescript-7-december-2025/

Main things to be aware of:

• typescript eslint may not work on tsgo, may need to keep tsc installed for it to continue working
• we need to raise our typescript targets to ES 2021. This should be fine since node 16 and up support it and we support node 18
• Install @typescript/native-preview and use tsgo in place of tsc references

[mikeldking]

un-assigning until we are more confident

[cephalization]

See #11588