WIP: various improvements (do not merge)

[maxholman]

• upgrade all deps
• general code org improvements
• remove redundant code
• improve ts configs
• node 22 as base
• drop node 18
• drop eslint/prettier
• remove b65 rds in examples
• remove triple slash references (avoid issues similar to TS2304: Cannot find name 'DOMHighResTimeStamp' #15 and TS2305: Module '"type-fest"' has no exported member 'Jsonifiable' #16 in future)
• better integration tests that dont involve fake subscriptions that expire or get unsubscribed

[maxholman]

Superseded by #19, which carries this branch's work plus the 2.0 encoding change. Both remaining checklist items here are done in it: the triple slash references are gone (verified by typechecking a consumer with lib: ["es2022"], types: [] and skipLibCheck: false against the packed tarball), and the integration tests no longer use fake subscriptions that expire.