feat: integrate nostrdb relay indexing

- Upgrade `nostrdb` to v0.6.1 with relay metadata support
- Switch to `nostr::RelayUrl` for typed relay URLs
- Use `process_event_with()` to pass relay info during ingestion
- Update `Relay`, `RelayPool`, and unknown ID logic accordingly

This enables richer indexing with relay provenance in events.

Signed-off-by: William Casarin <jb55@jb55.com>

crates/notedeck/Cargo.toml

@@ -12,6 +12,7 @@ strum = { workspace = true }
 strum_macros = { workspace = true }
 dirs = { workspace = true }
 enostr = { workspace = true }
+nostr = { workspace = true }
 egui = { workspace = true }
 eframe = { workspace = true }
 image = { workspace = true }