Re-dispatching the same agent on the same issue reuses the persistent workdir
via execenv.Reuse(), where the standard-provider skill refresh re-wrote skills
without clearing the prior dispatch's output, so allocateCollisionFreeSkillDir
dodged Multica's own directories into issue-review-multica-N.
On reuse, reclaim the platform-owned managed skill directories the prior
manifest recorded (removeReusedManagedSkillDirs) and roll back the remaining
sidecar files (CleanupSidecars) before refreshing, so each skill lands at its
canonical slug every dispatch. Mirrors the Codex hydrateCodexSkills wipe;
scoped to reuse, which never runs for local_directory tasks.
Fixes#3684 (MUL-2963).
d6a556bdbf