build: restore `libc` field on @optave/codegraph-linux-* entries in package-lock.json

[carlos-alm]

Deferred from PR #1138 review.

Original reviewer comment: Greptile review summary on #1138 (comment) ("libc discriminator silently removed from Linux optional packages").

Context: Greptile flagged this as a side-effect of the tree-sitter-erlang bump, but verification shows it is pre-existing on main (grep -c '"libc":' package-lock.json returns 0 on both branches). The published packages on npm do declare the field:

npm view @optave/codegraph-linux-arm64-gnu@3.10.0 libc → 'glibc'
npm view @optave/codegraph-linux-x64-gnu@3.10.0 libc → 'glibc'
npm view @optave/codegraph-linux-x64-musl@3.10.0 libc → 'musl'

Without the libc discriminator in the lockfile, on Linux x64 hosts npm matches both linux-x64-gnu and linux-x64-musl builds, and the runtime loader may load the wrong binary on musl (Alpine) hosts.

Suggested fix: Investigate why npm install strips the libc field from these entries (possibly an npm version or a missing libc declaration in the consuming root package.json's optionalDependencies metadata). Either restore the fields in the committed lockfile or amend the root package.json so they survive regeneration.

Out of scope for #1138 (a one-line devDependency bump that does not touch this section).