fix: Normalize package manager versions (#13177)
## Why
Package managers can report versions with a leading `v`, but
`devEngines.packageManager.version` must be an exact semver string
without that prefix. This caused repos generated by `create-turbo` with
`nub` to fail workspace resolution immediately.
## What
Normalize package manager versions before writing
`devEngines.packageManager`.
## How
Added a regression test for a `v0.2.10` package manager version and
verified `@turbo/workspaces` tests/typecheck.
