`--corepack-enabled` doesn't work with Node.js 25

[jessestricker]

Installing Node.js 25 (or later) does not work when also using the --corepack-enabled flag.
This is because as of Node.js 25, corepack is no longer bundled in the Node.js installation and has to be installed separately.

To reproduce, run the following:

$ fnm --version
fnm 1.38.1

$ fnm install 25 --corepack-enabled
Installing Node v25.0.0 (x64)
Enabling corepack for Node v25.0.0
error: Can't enable corepack: Can't spawn program: No such file or directory (os error 2)
Maybe the program /home/jesse/.local/share/fnm/node-versions/v25.0.0/installation/bin/corepack does not exist on not available in PATH?

As a workaround, do the following (once):

$ FNM_COREPACK_ENABLED=false fnm install 25
Installing Node v25.0.0 (x64)

$ fnm exec --using=25 npm install -g corepack

added 1 package in 136ms

$ fnm use 25 --corepack-enabled
Using Node v25.0.0

[jessestricker]

Maybe fnm can check whether corepack is bundled with Node.js and run npm install -g corepack after installing Node.js if it's not.

[kaaax0815]

I think this could be solved with #139