Revisit roles

[jbearer]

Currently the node supports a variety of modes (DA, archival, lightweight) which are implicitly determined by the optional modules a node runs. However, some functionality that certain roles should provide, they are not currently doing. E.g. lightweight nodes should at least store leaves and VID shares for a certain amount of time, but currently they do not. E.g. all nodes should store recent merklized states, but currently only archival nodes do this.

I think what needs to change is the following:

• availability module: add an option for storing leaves only
• make availability, node, state, status, and catchup modules required: all nodes should run these in some form or another
• define availability/node pruning settings:
  • archival: disabled
  • DA: retain at least 3 days, up to 1 week
  • lightweight: retain at least 3 days, up to 1 week, do not fetch or store payloads at all
• implement Merklized state pruning:
  • archival: disabled
  • DA/lightweight: retain only the last N states (N can be small, like 10), will be used for catchup only

All nodes can choose whether to use Postgres or SQLite backend. We strongly recommend Postgres for archival nodes.