chore: bump dev dependencies

[rokso]

Replaces #2, which fails CI.

Changes

• prettier 3.9.10, vitest 5.0.3 (supports Node 22.12+), typescript 6.0.3
• @types/node stays on 22, matching the lowest Node in engines
• Dependabot now ignores:
  • major @types/node updates, which move with the Node floor
  • typescript 6.1 and later, until typescript-eslint supports it (8.71 allows <6.1.0)

Why not #2

• TypeScript 7.0.2 breaks lint: typescript-eslint does not support it yet.
• @types/node 26 would type APIs that Node 22.13 lacks.

Checks

• Lint, typecheck, 245 tests, build and the CommonJS require pass.
• TypeScript 6 builds a dist identical to TypeScript 5.9, so the published code is unchanged.