Returns the paginated list of Avalanche Primary Network validator nodes that a user can delegate to,
for rendering the node-selection screen in a custodian wallet. Each item combines live P-Chain data
(sourced from platform.getCurrentValidators) with ContributionDAO overlay metadata (displayName,
isRecommended).

Because this returns the full network validator set (1,000+ nodes), always page through the results.
Use recommended=true to show only ContributionDAO-suggested nodes (e.g. a "Recommended" tab). Stake
amounts are AVAX decimal strings; availableCapacityAvax is computed as
min(5 x selfStake, 3,000,000 AVAX) - totalStaked and may be "0" when the validator is at capacity.

This endpoint is intended as a pre-check before building an AddPermissionlessDelegatorTx via
/avalanche/transactions/delegate: the delegation period must fall within the validator's
startTime/endTime window and the delegation amount must not exceed availableCapacityAvax.