P2-17 NativeEngine adaptive convergence + early exit

[Kinin-Code-Offical]

(Synced from docs/current_status/issue_ready_backlog.md)\n\n# P2-17 NativeEngine adaptive convergence + early exit\n\nSummary

• Area: NativeEngine circuit
• Deliverable: stop when residual small; optional damping.

Acceptance Criteria

• Non-linear iteration stops early when converged.
• Damping (optional) reduces oscillation on hard cases.
• Max-iteration behavior remains safe.

Test Plan

• Add circuits that converge quickly and verify fewer iterations.
• Add a hard circuit and verify stable convergence or graceful failure.

Likely File Targets

• NativeEngine non-linear solver loop

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