report: say which Zcash shielded tests never touch a device

Chasing a rendering defect on the per-output shielded confirm turned up
something worse than a missing screenshot: ZcashSignPCZT is never sent to a
device anywhere in this suite. Every test in test_msg_zcash_sign_pczt drives
a ScriptedTransport with canned responses -- they are offline contract tests
that prove the client builds and orders its messages correctly, and prove
nothing whatsoever about firmware behaviour.

The device-driven Zcash tests cover transparent signing, display-address,
FVK derivation and the seed fingerprint. None of them signs a shielded
output. So the on-device shielded path -- including the confirm screen that
fsm_msg_zcash.h designates as the verification gate for Orchard output
values, since total_amount is "a summary prompt" taken from the host -- has
no automated coverage at all.

The catalog gave no hint of this. The section Z entries read exactly like
the device tests around them, and that is how a screen nobody has ever
rendered sat behind seven green checks.

Say it in the entry instead. No screenshot hint: requesting frames from a
test that cannot reach a device would produce silently zero of them, which
is the same class of empty-but-green evidence this whole pass exists to
remove.

Verified: --screenshot-filter does not select it, and the report still
renders 325 tests and passes --validate-junit against the RC artifacts.

Author: BitHighlander

scripts/generate-test-report.py

@@ -2038,7 +2038,14 @@ def _arg_shown(a):
           'test_private_send_preserves_compact_real_spend_order',
           'Private send preserves real-spend signature order',
           'Compact device signatures remain ordered by the real-spend actions when dummy actions '
-          'are interleaved.',
+          'are interleaved. OFFLINE CONTRACT TEST -- like every test in test_msg_zcash_sign_pczt, '
+          'it drives a ScriptedTransport with canned responses and never reaches a device. It '
+          'proves the client builds and orders the messages correctly; it proves nothing about '
+          'firmware behaviour, and it can never produce an OLED frame. ZcashSignPCZT is not sent '
+          'to a device anywhere in this suite, so the on-device shielded signing path -- '
+          'including the per-output confirm that is the designed verification gate for Orchard '
+          'output values -- has no automated coverage at all. Shielded signing must be walked on '
+          'real hardware.',
           []),
          ('Z18', 'test_msg_zcash_sign_pczt',
           'test_missing_is_spend_is_rejected_before_device_call',