fix(core): relocate moved project checkouts

[Hona]

Summary

• detect an externally moved checkout only when the stable project ID matches and the stored primary path is specifically NotFound
• atomically promote the new primary path, rewrite root/nested session locations, invalidate session context epochs, and replace the project-directory record
• preserve existing live clone/worktree behavior and keep filesystem I/O off normal project opens/listing

Validation

• regression test fails on 71c3a7c8f (worktree remains the deleted path)
• same test passes on this branch, including concurrent relocation, nested sessions, epoch invalidation, and directory replacement
• existing live-clone guard passes on both dev and this branch
• project suite: 37 passed
• session runner suite: 80 passed
• core/opencode typechecks and pre-push monorepo typecheck pass
• real isolated opencode serve flow passes

Related: #27822 #25625 #29703 #29823 #30697 #31869 #31888

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[github-actions]

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