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/list_crdt.rs

@@ -299,9 +299,12 @@ where
     fn index(&self, idx: usize) -> &Self::Output {
         let mut i = 0;
         for op in &self.ops {
-            if !op.is_deleted && op.content.is_some() {
+            if op.is_deleted {
+                continue;
+            }
+            if let Some(content) = op.content.as_ref() {
                 if idx == i {
-                    return op.content.as_ref().unwrap();
+                    return content;
                 }
                 i += 1;
             }
@@ -318,9 +321,12 @@ where
     fn index_mut(&mut self, idx: usize) -> &mut Self::Output {
         let mut i = 0;
         for op in &mut self.ops {
-            if !op.is_deleted && op.content.is_some() {
+            if op.is_deleted {
+                continue;
+            }
+            if let Some(content) = op.content.as_mut() {
                 if idx == i {
-                    return op.content.as_mut().unwrap();
+                    return content;
                 }
                 i += 1;
             }