libSceKeyboard technical debt

sceKeyboardGetKey2Char: the original validates HID usages 4 through 231 before the handle and preserves unconverted HID usages in the output with processed == 0. The host instead accepts out-of-range usages and writes zero for unconverted keys. The original ignores the Kana LED, while the host throws for it. This partially implemented function contains NotImplemented_nid_no_patch(__func__); its body is preserved under the requested restriction.

sceDbgKeyboardClose, sceDbgKeyboardGetKey2Char, sceDbgKeyboardInit, sceDbgKeyboardOpen, sceDbgKeyboardRead, sceDbgKeyboardReadState (libSceKeyboard) - names and NIDs are present in the PS5 3.20 export inventory, but no credible prototypes were found. They are declared without parameters solely to resolve known imports; this is not an ABI claim.
sceKeyboardGetDeviceInfo and sceKeyboardSetProcessFocus: pointer arguments are passed to device ioctls. Device-info storage is 168 bytes in the connection-query caller, but its fields and the process-focus layout remain unresolved.
sceKeyboardConnectPort, sceKeyboardDisconnectPort and sceKeyboardDeviceOpen: argument widths are confirmed. The meaning/order of the two 32-bit port arguments and the final 32-bit device-open argument still require the device-service backend.
sceKeyboardPadEmulateClose and sceKeyboardPadEmulateOpen: the supplied keyboard library has neither export; their signatures remain unresolved.