Upgrade TypeScript 5 → 6

[strickvl]

Context

Dependabot PR #216 included typescript 5.9.3 → 6.0.2. This is a major version bump that was deferred from the safe batch update in #219/#220.

What to expect

TypeScript 6 may include:

• Stricter type checking rules
• Deprecated API removals
• New type system features that change inference behavior
• Possible breaking changes in compiler output

Steps

1. Create a branch and bump typescript to latest v6
2. Run npm run compile and fix any type errors
3. Check if ts-loader and typescript-eslint need updates for TS 6 compatibility
4. Run full test suite
5. Verify CI passes

Labels

dependencies