Extend channel policy queries and structs to support v2-specific fields:
- Add BlockHeight field to track the block height for v2 policy updates.
- Add DisableFlags field for v2 channel disable messages.
Both fields are nullable (sql.NullInt64/Int16) to maintain backwards
compatibility with v1 channels. The fields are initialized as null in
updateChanEdgePolicy and threaded through all policy-related queries
(GetChannelBySCIDWithPolicies, ListChannelsByNodeID, UpsertEdgePolicy,
etc.) and the extractChannelPolicies helper.
This commit includes both the hand-written SQL query updates and the
corresponding sqlc-generated Go code.
Elle Mouton
0aa93c93e7