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>

Cargo.toml

@@ -33,8 +33,8 @@ indexmap = "2.6.0"
 log = "0.4.17"
 nostr = { version = "0.37.0", default-features = false, features = ["std", "nip49"] }
 mio = { version = "1.0.3", features = ["os-poll", "net"] }
-nostrdb = { git = "https://github.com/damus-io/nostrdb-rs", rev = "22fa1cc57ee1b4ce10e726ab284bc124461c8871" }
-#nostrdb = "0.5.2"
+#nostrdb = { git = "https://github.com/damus-io/nostrdb-rs", rev = "ecae493712505f91488bea0b53aa5a7b50f44ab2" }
+nostrdb = "0.6.1"
 notedeck = { path = "crates/notedeck" }
 notedeck_chrome = { path = "crates/notedeck_chrome" }
 notedeck_columns = { path = "crates/notedeck_columns" }