This was figured out by Claude Code working autonomously over ~12 hours. It works, but overall it's worse than PDCurses. I cannot tell the difference in ccmake, but in gdb:

• Background colors, like line numbers being highlighted (slightly better)
• No support for C-a or C-e (big downgrade)
• Unrecognized modified keys are treated as unmodified, .e.g. M-f is f. PDCurses ignores M-f. (slightly worse)
• Neither can actually handle wide characters. (no change)

I wanted to capture this somewhere, and perhaps some of this could be addressed in the future.