Mazda: decouple TJA MADS from MRCC

[chinna244]

This makes the physical TJA button the MADS lateral-control source on the supported Mazda CX-5 platform instead of tying lateral availability to MRCC state.

The TJA state is preserved on synthetic CRZ_BTNS messages, while the forwarded copy to the FSC has the TJA bit cleared so stock TJA does not take ownership. Panda safety still receives the original bus-0 state.

Mazda can arm MRCC as a side effect of a TJA press. When that happens from an MRCC-off state, the controller sends a bounded MRCC_OFF cleanup after release. The cleanup keeps driver input priority, uses raw MRCC state for confirmation, preserves ownership across repeated TJA interaction, and is limited to three transmitted frames.

The behavior is scoped behind TJA_MADS. Mazda platforms without that capability continue using the existing MADS/MRCC path.

Required Panda dependency

This OpenDBC PR is not sufficient by itself. Panda must call the new safety_fwd_modify() hook on the copied forwarding packet. Without this call, the physical TJA bit is forwarded unchanged to the FSC and stock OEM TJA can still take ownership.

The required Panda change is commit 950151de. Add this one line in board/drivers/fdcan.h, after copying the RX payload into to_send and before recalculating its checksum:

(void)memcpy(to_send.data, to_push.data, dlc_to_len[to_push.data_len_code]);
safety_fwd_modify(bus_number, &to_send);
can_set_checksum(&to_send);

Required integration order:

1. Merge this OpenDBC PR so safety_fwd_modify() is declared and implemented.
2. Apply the one-line Panda fdcan.h change.
3. Update the Zoompilot OpenDBC and Panda submodule pins, then rebuild Panda firmware.

The complete combination—this OpenDBC work plus Panda 950151de—is already pinned and field-tested on the author's Zoompilot develop branch.

Tests

• 358 passed, 40 skipped
• forwarding isolation and lateral-source scoping
• raw MRCC state and cleanup ownership
• deadline/counter wrap/interruption cases
• OP cancel/resume interaction
• non-TJA Mazda regression coverage

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