Remove dead code and references: ffb module, OpenJVS HAT, ghost declarations, and invalid ENCODINGS macro

[Copilot]

Audit and removal of code that is compiled or declared but never reachable. The ENCODINGS macro was additionally invalid C syntax (array literal expression used as a macro).

Removed

• src/ffb/ — entire module deleted. initFFB(), bindController(), closeFFB() have no call sites outside the module. Removed ffb.c, ffb.h, the CMakeLists.txt source entry, and the stale #include "ffb/ffb.h" in modernjvs.c.
• src/jvs/io.h — getCapabilities() and getState() declared with no implementation in io.c and no call sites.
• src/jvs/jvs.h — DEVICE_ID, ENCODINGS (also syntactically invalid), STATUS_UNSUPPORTED, STATUS_OVERFLOW, REPORT_PARAMETER_ERROR2, REPORT_BUSY, and the JVS_STATUS_ERROR_UNSUPPORTED_COMMAND enum value — none referenced in any .c file.
• src/hardware/device.h — setupGPIO() and setGPIODirection() removed from the public header; both are only ever called within device.c via internal forward-declarations.

Note: DEVICE_ID, STATUS_UNSUPPORTED, STATUS_OVERFLOW, REPORT_PARAMETER_ERROR2, REPORT_BUSY, and JVS_STATUS_ERROR_UNSUPPORTED_COMMAND were subsequently restored per author request — only ENCODINGS remains removed.

Also, OpenJVS HAT dead code, references were removed.

Hardening

Tightened the setupGPIO return-value check from !setupGPIO() to setupGPIO() != 1 to be defensive against any future return-value range changes.

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[dazzaXx]

@copilot check if the PR branch needs updating as the master branch as changed since this PR was made.