chore(types): upgrade @types/node 24.13.3 to 24.13.6 (stay on Node 24)

[jasonhnd]

Series

Part of #635. Order 9. Blocked by order 8 (#644) merged to preview.

Why

@types/node ^24.13.3 → 24.13.6, the latest 24.x. npm "latest" is 26.x — do not take it:

• Builds run Node 24 (.nvmrc 24, CI node-version: 24.x, Vercel default 24.x).
• Vercel rejects Node 26 for Builds/Functions as of 2026-09-24 (Sandbox only); TOOLCHAIN §4 and §9.4 forbid @types/node@26. Node 26 is tracked in [UPGRADE] 2026-09 toolchain series (Astro 7.3, security overrides, Bun 1.4.2, TypeScript 7, CI actions v7) #635 "Not in this series".

sharp lists @types/node as an optional peer (*) — satisfied by 24.13.6.

Dry run 2026-09-24 (throwaway worktree: preview 9b4e7197 + orders 1–8 applied, Bun 1.4.2, Node 24.20.0, no PUBLIC_* env)

Step	Result
^24.13.6 → bun install	@types/node@24.13.6; lockfileVersion 1; diff = package.json 1 line, bun.lock 4 lines
typecheck (TS 7.0.2) / test / build / REQUIRE_BUILT_ARTIFACTS / verify:gates	all OK
bun x playwright test --reporter=line	356 passed, 26 skipped, 0 failed
bun audit	No vulnerabilities found

やること

1. Branch chore/types-node-24.13.6 from origin/preview (order 8 merged).
2. package.json devDependencies["@types/node"]: ^24.13.3 → ^24.13.6. Keep the ^24 major.
3. bun install, then:

   grep -n '"@types/node": \["@types/node@' bun.lock   # 24.13.6 — exactly one entry, major 24
   grep -n 'lockfileVersion' bun.lock                  # 1

4. Standard chain:

   unset PUBLIC_GA4_MEASUREMENT_ID PUBLIC_X_PIXEL_ID PUBLIC_META_PIXEL_ID
   bun run typecheck && bun run test && bun run build
   REQUIRE_BUILT_ARTIFACTS=1 bun test scripts/home-css-loading.test.ts src/site/models-built.test.ts
   bun run verify:gates
   bun x playwright test --reporter=line
   bun audit
   git diff --exit-code

5. Docs: docs/TOOLCHAIN.md §11 order 9 done + PR number (if §2 mentions @types/node, update it to 24.13.6). CHANGELOG.md ### Changed: - **@types/node 24.13.3 → 24.13.6** — stays on Node 24 (Vercel does not accept Node 26 yet).

やらないこと

• No @types/node@25 / @26. No engines.node (TOOLCHAIN §9.1). No .nvmrc change.
• No other package bumps.

Acceptance

• @types/node@24.13.6 only; lockfileVersion: 1; only package.json + bun.lock changed.
• Step 4 chain green.
• quality + Vercel green. TOOLCHAIN §11 + CHANGELOG updated.

Branch / PR

chore/types-node-24.13.6 → base preview, Closes #645.

[jasonhnd]

Done in #658 (merged into preview at 43d1e3b). Implemented by Grok 4.7 (reasoning effort high) via the #635 serial runner; guard checks passed (PR base preview, only allowed files changed, quality green).