fix: rust 1.95.0 clippy lints and matrix-sdk 0.17 API changes

Toolchain bump surfaced new lints (derivable_impls,
unnecessary_unwrap, unnecessary_sort_by, while_let_loop,
collapsible_match, unnecessary_option_map_or_else, cmp_owned)
across bft-json-crdt and huskies-server. All fixed mechanically.

Cargo.toml: dropped the no-longer-existing `rustls-tls` matrix-sdk
feature, then chased through the 0.17 API breakage:
- Relation::Reply is now a tuple variant wrapping Reply, not a
  struct variant with `in_reply_to`
- UserIdentifier::UserIdOrLocalpart removed — use
  UserIdentifier::Matrix(MatrixUserIdentifier::new(..))
- SendMessageLikeEventResult no longer exposes event_id directly;
  it's now on the inner `response` field

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/bft-json-crdt/src/json_crdt/value.rs

@@ -10,8 +10,9 @@ use crate::{keypair::AuthorId, list_crdt::ListCrdt, lww_crdt::LwwRegisterCrdt, o
 use super::{CrdtNode, CrdtNodeFromValue};
 
 /// An enum representing a JSON value
-#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
 pub enum JsonValue {
+    #[default]
     Null,
     Bool(bool),
     Number(f64),
@@ -61,12 +62,6 @@ impl Display for JsonValue {
     }
 }
 
-impl Default for JsonValue {
-    fn default() -> Self {
-        Self::Null
-    }
-}
-
 /// Allow easy conversion to and from serde's JSON format. This allows us to use the [`json!`]
 /// macro
 impl From<JsonValue> for serde_json::Value {