fix: do not throw when fs.close is getter-only

[dyk1454683243-sudo]

Fixes #257

Problem

On some Node / bundler setups (Vite, esbuild, ESM interop), require('fs') is a namespace-style object whose methods are getter-only. graceful-fs then does:

fs.close = function close () { /* queue reset */ }

and throws:

TypeError: Cannot set property close of #<Object> which has only a getter
    at graceful-fs.js:52

This shows up through fs-extra → graceful-fs when the dependency graph is pre-bundled.

Fix

• Assign fs.close / fs.closeSync only when the property is writable or has a setter.
• If it is getter-only but configurable, replace it with defineProperty.
• If it is getter-only and non-configurable, skip the global patch instead of throwing.
• Materialize getter-only properties on the cloned export so that lookalike can still be patched.
• If the real fs.close could not be assigned, still wrap close on the exported object so EMFILE retries keep working for graceful-fs callers.

Normal Node is unchanged: fs.close remains a writable data property, so the existing assignment path is used.

Tests

test/close-getter-only.js:

• configurable getter-only close is patched (defineProperty path)
• patched close / closeSync still open and close real file descriptors
• non-configurable getter-only close loads without throwing and leaves the real fs method alone
• clone() turns getter-only properties into writable data properties

Local npm test: 49460 passing.

Does not overlap with #261 (large writeFile).