fix: retire bootstrap after mise handover

[filipeforattini]

Summary

• make the standalone red-dev download temporary ownership once mise has acquired red-dev
• repair existing machines whose original handover migration was marked complete while the running bootstrap remained
• prove every alias replacement with mise where before removing any release-installed binary
• handle Windows file locking by cleaning the bootstrap after the child process exits

Validation

• git diff --check
• full shell/typecheck/test/build validation delegated to CI for this low-resource workstation

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