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>

server/src/chat/util.rs

@@ -156,10 +156,7 @@ fn is_inside_code_fence(text: &str) -> bool {
 pub fn drain_complete_paragraphs(buffer: &mut String) -> Vec<String> {
     let mut paragraphs = Vec::new();
     let mut search_from = 0;
-    loop {
-        let Some(pos) = buffer[search_from..].find("\n\n") else {
-            break;
-        };
+    while let Some(pos) = buffer[search_from..].find("\n\n") {
         let abs_pos = search_from + pos;
         // Only split at this boundary when we are NOT inside a code fence.
         if is_inside_code_fence(&buffer[..abs_pos]) {