feat: rewrite the nip-4e implementation (#1)

Make NIP-4e a core feature, not an optional feature.

Note:
- The UI is broken and needs to be updated in a separate PR.

Reviewed-on: #1

crates/common/src/constants.rs

@@ -2,12 +2,11 @@ pub const CLIENT_NAME: &str = "Coop";
 pub const APP_ID: &str = "su.reya.coop";
 
 /// Bootstrap Relays.
-pub const BOOTSTRAP_RELAYS: [&str; 5] = [
+pub const BOOTSTRAP_RELAYS: [&str; 4] = [
     "wss://relay.damus.io",
     "wss://relay.primal.net",
     "wss://relay.nos.social",
     "wss://user.kindpag.es",
-    "wss://purplepag.es",
 ];
 
 /// Search Relays.
@@ -28,8 +27,5 @@ pub const NOSTR_CONNECT_TIMEOUT: u64 = 200;
 /// Default timeout (in seconds) for Nostr Connect (Bunker)
 pub const BUNKER_TIMEOUT: u64 = 30;
 
-/// Total metadata requests will be grouped.
-pub const METADATA_BATCH_LIMIT: usize = 20;
-
 /// Default width of the sidebar.
 pub const DEFAULT_SIDEBAR_WIDTH: f32 = 240.;