Migrate platform to the new SML structure (Core 23 nested masternode platform addresses) #3939

Background

rust-dashcore#808 introduced a new Simplified Masternode List (SML) structure for Core 23 (DEPLOYMENT_V24): masternode platform endpoints move into a nested addresses object (MasternodeAddresses) that decouples the platform host/ports from the core service address, and the flat platformP2PPort / platformHTTPPort fields become deprecated (legacy_*). Only the incremental protx listdiff path is affected (full-state addedMNs still reconstructs the legacy shape).

Platform PR #3936 migrated drive-abci to this structure:

• resolved masternode platform ports through the new platform_p2p_address() / platform_http_address() accessors (nested-first, non-zero legacy fallback) so Core 23 (ProTx v3) entries are no longer dropped from validator sets;
• corrected the incremental-diff validator refresh/removal trigger;
• persisted the split platform/core host via a new versioned MasternodeStateV1 / Masternode::V1, gated to protocol v12 (a drive_abci.structs.masternode struct-version bump) — a consensus-version-coupled change.

Decision

The temporary SML changes are being reverted from dashcore for now, so we avoid a consensus / protocol-version change at this time. The corresponding platform changes — the Core 23 port resolution and especially the MasternodeStateV1 / v12 struct-version bump — are being reverted from #3936. #3936 stays scoped to the dashcore rev bump for rust-dashcore#813 (DashPay account-index derivation path).

What needs to happen (this issue)

When dashcore re-introduces the new SML structure (permanently), migrate platform to it:

• Bump rust-dashcore to the rev that lands the new SML structure.
• Resolve masternode platform ports via the nested addresses accessors (drop the flat-port assumption), keeping the Core 22 legacy fallback.
• Fix the incremental-diff validator refresh/removal trigger as a superset of the validity predicate (fires on zeroed-legacy-port and platform_node_id deltas the port resolvers drop).
• Persist the split platform/core host (MasternodeStateV1 + a struct-version bump tied to the protocol version that activates the new SML). Note: the persisted masternode/validator-set state is local, non-consensus aux-CF state (not in app_hash), but the struct-version bump must still ride a protocol version per convention.
• Bracket IPv6 platform hosts in the reconstructed addresses (round-trip safety — an unbracketed 2001:db8::1:443 is unparsable and drops the HPMN).

Reference: the reverted implementation

The full implementation is preserved in #3936's history and can be re-applied:

References

• dashcore (original SML structure): fix(rpc-json)!: resolve Core 23 nested platform addresses (breaking field/accessor renames) rust-dashcore#808
• platform (reverted migration): chore(drive-abci): update to nested address in SML #3936