Add Neptune Orca CAN APIs

[drebbe-intrepid]

Adds CAN communication support for FreeWili devices with Neptune Orca hardware (I2C address 0x48).

CAN APIs Added

• can_transmit() - Send CAN/CAN-FD messages on channels 0-1
• can_enable_streaming() - Enable/disable CAN RX event streaming
• can_set_transmit_periodic() - Configure periodic message transmission (8 slots per channel)
• can_enable_transmit_periodic() - Start/stop periodic transmission
• can_set_rx_filter() - Configure hardware RX filters (32 filters per channel)
• CANData.from_string() - Parse CAN event data with error handling for empty payloads

Testing

• Comprehensive test suite in test_can.py with hardware detection
• Tests use @pytest.mark.xfail to gracefully handle missing Neptune hardware
• Updated I2C tests to skip when Neptune is present (avoids false failures)

Documentation

• Added CAN, WilEye, and file download examples to examples.rst
• Fixed file mapping: .py files now correctly labeled "Python script"

[drebbe-intrepid]

@copilot code review please

[Copilot]

@drebbe-intrepid I've opened a new pull request, #30, to work on those changes. Once the pull request is ready, I'll request review from you.