Show historical support

[jtourkos]

Description

Projects show earnings from historical supporters but empty support lists when those supporters later change their splits configuration. For example, a project displays "$$ in donations" but "0
supporters" because the supporter updated their splits to exclude that project. This creates user confusion about where funds came from.

Cause:

• totalEarned queries permanent split_events table (historical data)
• support queries splits_receivers table (current configuration, gets wiped/recreated on updates)

Proposed Solution

Query split_events for non-existing senders and return "active" and "historical" supporters

Related: #78

[efstajas]

• we also need to be able to return historical (deleted) streams