chore: prepare for rc version (#34)

**TODOs:**

- [x] Fix all clippy issues
- [x] Make NIP-4e optional (disabled by default)
- [x] Remove support for bunker (Nostr Connect)
- [x] Group messages in the same timeframe
- [ ] ...

Reviewed-on: https://git.reya.su/reya/coop/pulls/34

crates/state/src/nip4e.rs

@@ -0,0 +1,55 @@
+use gpui::SharedString;
+use nostr_sdk::prelude::*;
+
+/// Announcement
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Announcement {
+    /// The public key of the device that created this announcement.
+    public_key: PublicKey,
+
+    /// The name of the device that created this announcement.
+    client_name: Option<String>,
+}
+
+impl From<&Event> for Announcement {
+    fn from(val: &Event) -> Self {
+        let public_key = val
+            .tags
+            .iter()
+            .find(|tag| tag.kind() == "n")
+            .and_then(|tag| tag.content())
+            .and_then(|c| PublicKey::parse(c).ok())
+            .unwrap_or(val.pubkey);
+
+        let client_name = val
+            .tags
+            .iter()
+            .find(|tag| tag.kind() == "client")
+            .and_then(|tag| tag.content())
+            .map(|c| c.to_string());
+
+        Self::new(public_key, client_name)
+    }
+}
+
+impl Announcement {
+    pub fn new(public_key: PublicKey, client_name: Option<String>) -> Self {
+        Self {
+            public_key,
+            client_name,
+        }
+    }
+
+    /// Returns the public key of the device that created this announcement.
+    pub fn public_key(&self) -> PublicKey {
+        self.public_key
+    }
+
+    /// Returns the client name of the device that created this announcement.
+    pub fn client_name(&self) -> SharedString {
+        self.client_name
+            .as_ref()
+            .map(SharedString::from)
+            .unwrap_or(SharedString::from("Unknown"))
+    }
+}