chore(tsconfig): typecheck scripts/ and tests/, then exhaustively type NAME_KINDS/DIR_KINDS

[dean0x]

Finding

Two related pre-existing typescript findings:

1. typescript-5: scripts/ and tests/ are never type-checked — tsconfig.json:18's include is src/** only, so type errors in scripts/ and tests/ are invisible to any typecheck gate.
2. typescript-6: NAME_KINDS/DIR_KINDS in tests/mds-variants.test.ts:195,198 are subset-typed (not exhaustively checked against the full Kind union).

Why deferred together

typescript-6's fix (satisfies Record<Kind,true>) only bites once a typecheck gate actually covers tests/** — i.e. once typescript-5 is fixed. Landing typescript-6 alone would add a stricter type annotation that no CI step verifies. They must land together.

Why deferred (not fixed in PR #334)

Pre-existing before this PR. Adding a check-only tsconfig plus a typecheck gate that covers scripts/** and tests/** is likely to surface an unknown backlog of existing type errors across tests/**, which is out of scope for a plumbing-only phase PR (#334, Tracker Phase 1).

Suggested fix

1. Add a check-only tsconfig.json (or a second include scope) covering scripts/** and tests/**, wired into a typecheck script/gate in package.json.
2. Fix whatever backlog of type errors that gate surfaces in tests/**/scripts/**.
3. Once the gate is green, change NAME_KINDS/DIR_KINDS in tests/mds-variants.test.ts:195,198 to satisfies Record<Kind,true> so a future Kind addition is caught at typecheck time instead of silently falling out of sync.

References

• Source review: .devflow/docs/reviews/feat-323-tracker-phase-1-mds-plumbing-provably-by/2026-09-09_2237
• PR: refactor(build): compile the Git agent from an MDS generator host #334
• Finding IDs: typescript-5, typescript-6
• Files: tsconfig.json:18, package.json, tests/mds-variants.test.ts:195,198