feat(icom): add native Band Zoom and Segment Zoom

[jensenpat]

Summary

Enable the existing Band Zoom and Segment Zoom controls on scope-capable Icom radios. The buttons and shortcut/controller paths now share the backend's zoom capability declaration. For Icom, the active band plan supplies the target edges and the app requests the smallest native scope span that covers them around the radio-reported center. FlexRadio keeps its radio-owned zoom flag behavior.

Constitution principle honored

Principle II — the radio owns the scope center and confirms its geometry; the client requests only a supported span. The Icom declaration is backed by the existing setPanBandwidth verb and its detent table.

Validation

• Rebased onto aethersdr/main at cedd50f4e and signed commit f6545d289.
• Passed strict engine-boundary, command-plane, capability-record, CI test-gate, and test-registration checks; touchpoint manifest and diff checks passed.
• Local build attempted. Current main requires Qt 6.12; this machine has Qt 6.11 and Command Line Tools but no full Xcode, so the pinned Qt installer stopped at its prerequisite check. Current-change CTest and automation bridge validation were not run.
• Native Icom scope behavior and laptop deployment remain unverified. The bridge's demo backend cannot exercise CI-V scope span commands. Hosted CI and a real-radio receive-only check are the next validation steps.

Test plan

• Hosted macOS/Linux builds and focused band_plan_zoom_test / icom_scope_test pass.
• On a scope-capable Icom, confirm B/S enable after scope geometry arrives, choose native spans, and leave tuned frequency unchanged.
• Check FlexRadio B/S flags still toggle and non-capable backends keep controls disabled.

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