feat(leios-tui): visualize the RB/EB overlay as aligned swim lanes

Reframe the dashboard as an educational view of the Leios overlay:
ranking blocks and endorser blocks render as boxes in two tip-following
lanes sharing one column axis, so an EB sits under the RB it belongs to
and the shared column is the connection. The EB→RB association is a slot
heuristic (nearest following RB) since no on-wire message links them;
BlockAnnouncement decoding is left as a hook for when the devnet diffuses
announcements. EB boxes show tx-download and vote bars plus a per-phase
checklist; RB boxes show a derived block hash and slot. Also refreshes
the chain-sync intersect point to a current tip.

Author: scarmuega

examples/leios-tui/Cargo.toml

@@ -11,6 +11,7 @@ release = false
 [dependencies]
 pallas-network2 = { path = "../../pallas-network2" }
 pallas-codec = { path = "../../pallas-codec" }
+pallas-crypto = { path = "../../pallas-crypto" }
 hex = "0.4.3"
 tokio = { version = "1.27.0", features = ["rt-multi-thread", "macros", "time"] }
 tracing = "0.1.41"