* fix: preserve pnpm 10 peer suffix encoding for linked paths
The filenamify upgrade from v4 to v7 changed the peer-suffix "version"
token for linked dependency paths: `../packages/b` became `+packages+b`
instead of `packages+b`, causing lockfile churn for workspaces with
packages linked from outside the workspace root.
Replace the filenamify call with a small inline encoder that reproduces
v4's output for link paths, and drop the now-unused dependency.
Closes#11272.
* chore: avoid cspell-flagged word in peer suffix comment
* test: cover linkPathToPeerVersion and clarify its lossy encoding
Address Copilot review feedback on #11297:
- Correct the comment — any leading run of `.` is dropped, not just
`./` and `../` segments (so `.hidden/pkg` becomes `hidden+pkg`).
- Export the helper and add a focused test that pins the exact token
output for link paths, so future lockfile-breaking regressions get
caught by the test suite.
* refactor: extract linkPathToPeerVersion into its own file
