Migrate express.static.mime

In Express 5, mime is no longer an exported property of express.static. The
mime-types package should be used to
work with MIME type values instead.

This codemod rewrites every express.static.mime reference to use a mime-types
binding and adds the corresponding import/require to the file:

1. Replaces express.static.mime with a mime-types local binding (default name mime).
2. Adds the import once per file, matching how express is imported
   (import mime from 'mime-types' for ESM, const mime = require('mime-types') for CommonJS).
3. Reuses an existing mime-types import when the file already has one, and falls
   back to a non-colliding name (mimeTypes) when mime is already taken.

The object Express 4 exposed as express.static.mime was a mime@1.x
instance, whose API is not identical to mime-types. The codemod rewrites
each member accordingly:

Example

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  import express from 'express'
+ import mime from 'mime-types'

- const type = express.static.mime.lookup('json')
+ const type = mime.lookup('json')

Renamed method

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- const charset = express.static.mime.charsets.lookup('text/html')
+ const charset = mime.charset('text/html')

Methods without a mime-types equivalent

define, load, and default_type cannot be migrated automatically, so the
codemod points them at the new binding and flags them for manual review:

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- express.static.mime.define({ 'text/x-custom': ['cstm'] })
+ mime.define({ 'text/x-custom': ['cstm'] }) /* TODO: 'mime-types' has no define(); migrate manually */

CommonJS

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  const express = require('express')
+ const mime = require('mime-types')

- express.static.mime.lookup('json')
+ mime.lookup('json')

package.json

For projects that depend on express, the codemod also adds mime-types to the
same dependency section, so the newly referenced package is declared:

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  "dependencies": {
-   "express": "^5.0.0"
+   "express": "^5.0.0",
+   "mime-types": "^3.0.0"
  }

An existing mime-types entry is left untouched, and package.json files without
express are not modified.

Notes

• Behavior differs slightly even for the shared methods: mime-types returns
  false for unknown input, whereas mime@1.x lookup() fell back to
  default_type (application/octet-stream). Review code that relied on that
  fallback.
• Members flagged with a TODO comment (define, load, default_type) have no
  mime-types equivalent and must be migrated by hand.
• Run npm install after the migration so the added mime-types dependency is installed.

References

• Express 5 Migration Guide - express.static.mime
• mime-types package