feat: Add dynamic sync mode to peer_network_interface

[whankinsiv]

Description

This PR introduces a new dynamic sync mode to the peer_network_interface. In this mode, the interface waits for a ChangeSyncPoint command on the cardano.sync.command topic and begins fetching from that point.

A background task forwards incoming sync points to the NetworkManager. When a new point arrives, the manager resets the ChainState, clears outstanding peer requests, and issues a new find_intersect across all upstream peers.

A minimal indexer process is included to demonstrate this behavior. It registers only the required modules and emits two ChangeSyncPoint commands 5 seconds apart, demonstrating dynamic re-syncing.

Related Issue(s)

#374

How was this tested?

By running the indexer process:

1. It publishes a sync point at the last Byron block.
2. The peer_network_interface begins fetching blocks normally.
3. A second ChangeSyncPoint is published, returning to the starting point.
4. The peer_network_interface resets and syncs again from that point.

For visibility, you can log inside handle_roll_forward to observe block fetching.

Checklist

• My code builds and passes local tests
• I added/updated tests for my changes, where applicable
• I updated documentation (if applicable)
• CI is green for this PR

Impact / Side effects

Adds a basic indexer process intended to become the minimal working example for building custom indexers on top of Acropolis.

Reviewer notes / Areas to focus

• Dynamic NetworkManager construction in peer_network_interface/src/peer_network_interface.rs.
• Correct behavior of on_sync_cmd when resetting sync state in peer_network_interface/src/network.rs.

[sandtreader]

This is really nice, and I agree with all of Simon's tweaks. I like the forward thinking for subsequent commands from consensus and the simplicity of the demo indexer!