types: mark DecoratorHandler as @deprecated

[kilisamemarisaaa]

This relates to...

Follow-up to #5707, which added @deprecated to lib/handler/decorator-handler.js (shipped in v8.10.1). No existing issue or PR tracks this — found by comparing the runtime deprecation against types/handlers.d.ts.

Rationale

DecoratorHandler is marked @deprecated at runtime since v8.10.1, but the type declaration in types/handlers.d.ts carries no @deprecated JSDoc tag and no deprecation marker anywhere in docs/. TypeScript consumers importing DecoratorHandler (or using it through the globalThis install) get no deprecation signal in their editors — the runtime and the types currently disagree about the class's status.

Changes

• Adds a @deprecated JSDoc tag with migration guidance (Use a plain handler object instead.) to DecoratorHandler in types/handlers.d.ts, matching the runtime annotation. The tag propagates to the index.d.ts re-export and the globalThis install, so editors will show the deprecation for all import paths.

Features

N/A

Bug Fixes

N/A (types annotation only — aligns the published types with the already-shipped runtime deprecation)

Breaking Changes and Deprecations

None — this change documents an already-existing deprecation; it does not deprecate anything new or alter any runtime behavior.

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested (npx tsd, tsc test/imports/undici-import.ts --noEmit, tsc types/*.d.ts --noEmit — all pass; test:typescript glob step verified equivalent)
• Benchmarked (S — not applicable)
• Documented (S — the deprecation note itself is the change; no DecoratorHandler doc page exists, and adding one for a deprecated class seemed out of scope)
• Review ready
• In review
• Merge ready