P2-18 NativeEngine circuit islanding

[Kinin-Code-Offical]

(Synced from docs/current_status/issue_ready_backlog.md)\n\n# P2-18 NativeEngine circuit islanding\n\nSummary

• Area: NativeEngine circuit
• Deliverable: partition graph and solve islands separately.

Acceptance Criteria

• Circuit graph is partitioned into independent islands.
• Solver runs per-island and produces same result as monolithic solve.

Test Plan

• Two disconnected circuits in one scene: verify each solves independently.

Likely File Targets

• NativeEngine circuit graph representation

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