fix(dash): make feed_qr_info resilient to missing rotation CL sigs

QRInfos that span a block range with no successful rotating DKG arrive with per-diff CL sigs missing. Previously this hard-errored with `RequiredRotatedChainLockSigNotPresent`. Now affected entries land as `Skipped(MissingRotationChainLockSigs)` and the cycle is left unstored, deferring IS lock verification for that cycle until a later QRInfo carries complete sigs.

Tighten the `rotated_quorums_per_cycle` insertion gate: store a cycle only when every entry is `Verified`, and never overwrite an already-fully-verified cycle (a thin follow-up QRInfo must not downgrade prior trust).

Add a previous-cycle storage path (`validate_and_store_previous_cycle_quorums`) that uses the 4 historical sigs `[h-3c, h-2c, h-c, h]` to validate and store the rotated quorums living on `masternode_lists[h]` under their cycle boundary hash. This enables IS lock verification for the previous cycle on a fresh sync, where `lastCommitmentPerIndex` only covers the current cycle.

Change `feed_qr_info` to return `Result<Option<QRInfoFeedResult>>` so callers can observe rotated quorum counts, fully-verified counts, and which cycle (if any) was stored.

New tests cover the soft-skip storage gate, corrupt aggregate-signature rejection, and the anti-clobber guarantee. The existing `validate_from_qr_info_and_mn_list_diffs` test is extended to assert both cycles are stored and to re-validate every stored quorum.

Author: xdustinface