[joeblau]

Replaces tsc (TypeScript 6.0.3) with tsrs, a Rust port of the TypeScript 7 compiler, for build:ts and build:ts-test in @bloxwap/chart. tsrs is pinned exactly (0.18.0-ts7.1.0-dev.20260929) because it is still pre-1.0. apps/docs keeps typescript, since Next.js needs it.

Parity (all gates passed before migrating)

Check	TS 6.0.3	TS 7.0.2	TS 7.1.0-dev.20260930.4	tsrs 0.18.0
Build + test build	ok	ok	ok	ok
Tests (1,897)	all pass	all pass	all pass	all pass
Emitted files vs tsrs (782)	118 .map differ, all .js/.d.ts identical	byte-identical	byte-identical	—
Diagnostics on an error probe (5 errors, incl. exactOptionalPropertyTypes)	identical	identical	identical	—

The only difference from TS 6 is source-map mappings granularity, which is a TypeScript 7 change (TS 7.0.2 produces the same maps as tsrs). npm run coverage after the switch: 100% on all 139 rows.

Timing (box, 8 vCPU, median of 7 interleaved runs)

	TS 6.0.3	TS 7.0.2	TS 7.1 dev	tsrs
Type check (tsconfig.test.json --noEmit)	3.23 s / 542 MB	0.42 s / 277 MB	0.37 s / 230 MB	0.14 s / 112 MB
Build (tsconfig.json, emit)	2.01 s / 352 MB	0.22 s / 148 MB	0.22 s / 144 MB	0.11 s / 68 MB

tsrs is about 23x faster than TS 6 at type checking and 3x faster than TS 7, with roughly a fifth of TS 6's memory. Lockfile includes the @tsrs/darwin-arm64 binary used by the self-hosted Mac mini runners.

Rollback is a one-line revert of package.json scripts plus the typescript devDependency.