OptimizedNodeBridge should prevent calls after dispose

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Summary

OptimizedNodeBridge sets disposed=true but call/instantiate/callMethod do not check it. Calls after dispose() can spawn new workers and continue executing, violating the expected lifecycle.

Failure mode

• bridge.dispose() is called.
• A subsequent bridge.call() still executes, spawning new processes.

Evidence

• src/runtime/optimized-node.ts call/instantiate/callMethod/executeRequest do not guard on this.disposed.

Proposed fix

• Add a guard that throws BridgeDisposedError in executeRequest (or in public methods).
• Ensure dispose() prevents any new work from being scheduled.

Acceptance criteria

• Calls after dispose reliably throw BridgeDisposedError and do not spawn processes.
• Add a regression test for use-after-dispose.

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✅ Resolved in PR #136: refactor: unify NodeBridge and OptimizedNodeBridge (ADR-0001)

The unified NodeBridge now throws BridgeDisposedError when call() or init() is invoked after dispose(). This matches the error type used consistently across all bridge implementations.