fix(keymap): not shadow keymap desc so make blink.cmp happy

[tim3nd]

fix Saghen/blink.cmp#441

Currently blink.cmp use desc to identify blink.cmp keymap, so shadow decs option in lean.nvim would make stack overflow in blink.cmp side.

I think this should mainly be handled for blink.cmp, but restore desc option after cleanup by lean.nvim seems also a reasonable default.

[Julian]

Thanks, I've seen this error myself in playing with blink.cmp and had no idea why I couldn't see where it was being caused.

[tim3nd]

Just FYI, blink.cmp use desc here to deduplicate of the fallback keymap configuration. :)
I also tried to improve this in blink.cmp but haven't found a clear and suitable method yet.