Remove thread-stream patch-package workaround after upstream fix

[samayer12]

Describe what should be investigated or refactored

Remove the temporary patch-package workaround for pinojs/thread-stream once upstream releases the fix for the Node 26 type declaration issue.

This repository currently patches thread-stream's TypeScript declaration to replace workerThreads.TransferListItem[] with workerThreads.Transferable[] so @types/node@26 can be used without TS2694.

Links to any relevant code

• Upstream issue: index.d.ts uses removed worker_threads.TransferListItem (@types/node@26) pinojs/thread-stream#228
• Upstream PR: Update transferList type in emit method signature pinojs/thread-stream#233
• Local patch file: patches/thread-stream+4.0.0.patch
• Install hook: package.json postinstall script
• CI verification: .github/workflows/on-demand-workflows.yaml

Additional context

Removal criteria:

• A released thread-stream version includes the Transferable[] declaration fix.
• The repo consumes that fixed version through pino/thread-stream resolution.
• npm run build passes with @types/node@26 without the local patch.

Cleanup tasks:

• Delete patches/thread-stream+*.patch.
• Remove patch-package from devDependencies and package-lock.json if no other patches remain.
• Remove the postinstall patch-package script if no other patches remain.
• Remove explicit patch-package CI verification if no other patches remain.