[Bug] Race condition in task claiming allows duplicate execution in multi-worker swarms

Bug Description
Title: Race condition in swarm task claiming

Issue:
TaskList → TaskUpdate has no atomic claim. Multiple workers can claim and execute the same task.

What happened:
3-worker swarm, 6 tasks. Both alpha and beta saw Task #=1 available, both claimed it, both executed it (duplicate web searches). Same race occurred on Task 4.

Evidence: Both workers messaged me "Completed Task 1" — beta won the final JSON write, but both did all the work.

Fix:
Atomic claim: TaskClaim(taskId, ifOwnerIs: null) that fails if already claimed.

Impact:
Wasted compute, potential file conflicts, breaks the self-organizing swarm pattern.

Environment Info

• Platform: darwin
• Terminal: tmux
• Version: 2.1.27
• Feedback ID: a3306fa4-6ecb-48a8-bc87-91991fbf5e84

Errors

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