Ramon benchmark for Z3
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Job description: 
Job tag: smt_qfnia-threads-4-smts_bugfix
Runner: rise-runner-2
Z3 repo: ilanashapiro/z3
Z3 commit: b341c61fbc65e5f4a330641d116d2e796f7cfb5d
Z3 branch: smts_tree_algorithms_bugfix
Z3 options: "-T:60 -v:0 smt.threads=4 tactic.default_tactic=smt smt.auto_config=false"
Z3 inputs: inputs/QF_NIA_small
Z3 commit message: first attempt with codex. Codex notes:
What changed:

  - Each tree node now tracks:
      - active worker count
      - lease epoch
      - cancel epoch
  - get_cube() now hands each worker an explicit lease: (node, epoch, cancel_epoch).
  - try_split() and backtrack() now operate on that lease, and the batch manager releases the worker’s lease under the tree lock before mutating the
    node.
  - If another worker closes the leased node or subtree, the batch manager cancels only the workers whose current leased nodes are now closed.
  - Workers detect canceled leases after check(), reset their local cancel flag, abandon the stale lease, and continue instead of turning that into a
    global exception.
  - The “reopen immediately into the open queue” policy is preserved. I did not add a barrier waiting for all workers on a node to finish.
  - Active-worker accounting is now separate from the open/active/closed scheduling status, so reopening a node no longer erases the fact that other
    workers are still on it.

  I also updated search_tree bookkeeping so:

  - closure bumps node cancel/lease epochs
  - active-node counting uses actual active-worker presence, not just status == active
