fix(emulator): show confirm button for zcash address + eth verify-message view-on-device

[BitHighlander]

Fix: emulator "view on device" hangs with no confirm button

Reported: in the emulator, Zcash "view address on device" (and similar view-on-device flows) show the OLED screen but have no button to press Accept, so it feels stuck.

Root cause

On a real device the user presses a physical button. On the emulator there's no button, so on-device display/confirm prompts must be wrapped in emuSigningOp(), which installs the ButtonRequest handler that surfaces the Confirm/Reject affordance in the emulator window (and writes the DebugLinkDecision press).

Every standard getAddress display handler does this (engine.isEmulator && params.showDisplay → emuSigningOp). Two handlers skipped the gate and called the wallet directly, so the firmware busy-loops in confirm_helper() with no UI button until the 120s confirm timeout:

• zcashDisplayAddress — view Orchard address on device (the reported bug)
• ethVerifyMessage — verify-message shows the message + address on device and waits for a press (its Tron counterpart tronVerifyMessage was already gated)

Fix

Wrap both in emuSigningOp() when engine.isEmulator, matching the existing pattern. No behavior change on real devices.

Sibling audit

• All *GetAddress display handlers, ethSignMessage, solanaSignMessage, tonSignMessage, ethSignTypedData, tronVerifyMessage — already gated. ✅
• Flagged separately (not touched here): an early terse eth handler cluster (ethSignTx/ethSignMessage/ethSignTypedData, ~index.ts:683-685) appears to be a different RPC object and is ungated — needs a separate look to confirm whether it's emulator-reachable.

Verification

• Typecheck clean (0 errors in index.ts).
• Needs an emulator smoke test: trigger Zcash "verify on device" and ETH verify-message in the emulator → Confirm/Reject buttons should now appear.