I think the closest rule that could arguably be applied is the one regarding infinite loops. From the NISEI Comprehensive Rules Document:
10.10. Infinite Loops
10.10.1. If a mandatory infinite loop is created (a player cannot choose to stop resolving the loop) then the player who is resolving the loop chooses a number. The loop instantaneously resolves that many times, and then ends. Example: The Runner runs into a rezzed Wormhole. The only other piece of ice that is rezzed is a Wormhole, and so a mandatory infinite loop is created where each the Wormholes’ subroutines resolves the other. The Corp chooses how many times this loop occurs, say 2,157 times, and then the Runner continues the run.
10.10.2. If an optional infinite loop is created (a player can choose to stop resolving the loop) during a run, then the Runner must jack out unless another card ability prevents them from doing so. If the Runner cannot jack out, then it is the Corp’s
responsibility to end the loop by letting the Runner continue the run.
The same text can be found in the last published FFG Rule Reference (v1.1).
I suppose an argument could be made that if such a stalemate situation occurs and it can be known to both players that there is no way to end the game, it could be treated as an optional infinite loop, which would mean the Corp would be compelled to break it (by choosing not to Hades Shard a card back into R&D and therefore losing by being decked/milled).
However, the rule above specifically talks about infinite loops which can occur in the context of a single run, rather than game states which cannot produce a result in either players' favour. Additionally, applying this rule as described above clearly gives an advantage to the Runner (although I would personally argue this is fine against any Corp trying to force a draw through infinite recursion).
So I think the short answer is that no, there isn't a specific ruling which deals with this (extremely unlikely) situation. But I'd be interested to hear from anyone else who knows otherwise.
Edit: jakodrako (co-creator of ANCUR and current NISEI Rules Manager) has stated here that the infinite loop rules are one of the areas on their list of things to investigate, so he's definitely aware of this.