[claude]

Requested by Łukasz Komoszyński · Slack thread

Upgrades the workspace to TypeScript 6.0.3, done properly with a real tsconfig migration so it compiles cleanly with no ignoreDeprecations.

Stacked on #163 (chore/npm-dependencies-bump). That PR keeps TypeScript on 5.9.3; this branch is based on it and carries only the TS 6 upgrade. Review/merge #163 first.

Why a separate PR

TypeScript 6 turns several long-tolerated tsconfig options into hard errors (they were previously only suppressible with ignoreDeprecations: "6.0"). Rather than paper over them, this PR removes the deprecated options for real.

tsconfig migration

• Removed baseUrl from tsconfig.base.json. Since TS 4.1, paths are resolved relative to the tsconfig's own location when baseUrl is absent, so every paths entry is now relative (prefixed with ./). No source relies on baseUrl-relative bare imports, so module resolution is unchanged.
• Migrated moduleResolution node → bundler in tsconfig.base.json. The old value (node/node10) is deprecated in TS 6. bundler is the org standard (matches js_corelibrary's tsconfig.base.json) and the correct mode for this package: module stays esnext, the sources use extensionless relative imports, and the emitted output is consumed/bundled downstream. module/target/lib are unchanged, so the emitted JavaScript is byte-identical (moduleResolution and baseUrl only affect compile-time resolution, not emit).
• Bumped tools/tsconfig.tools.json target es5 → es2022. The ES5 target is also deprecated in TS 6; es2022 aligns it with tsconfig.base.json.

Dependency

• typescript 5.9.3 → ^6.0.3 (lockfile regenerated). TS 6.0.3 sits inside typescript-eslint@8.64's peer range (<6.1.0), so lint is unaffected.

Verification

On Node 24.18: fresh strict npm install and npm ci both resolve cleanly (exit 0); nx run-many -t lint build test is green (lint 10 projects, build 9 projects, test 31 tests / 23 snapshots). A tsc --noEmit sweep across every project tsconfig reports no TS5107/TS5101 deprecation diagnostics, and there is no ignoreDeprecations anywhere in the tree.