refactor: resolve all lint findings

- remove 34 trivial restating comments (auto-fix)
- replace all 20 production .unwrap() calls with graceful handling:
  ?-propagation via LockPoisoned, unwrap_or_default on infallible
  conversions, let _ = on actor-channel sends, and a downloads_sender()
  helper in the TUI that also dedupes three channel-init blocks
- collapse nested if into match guard (clippy::collapsible_match)
- split client.rs (2275 lines) into a client/ module: connection,
  search, downloads, uploads, rooms, operations
- split ui/main_tui.rs (2027 lines) into a main_tui/ module: render,
  input, browse, rooms, downloads, search
- extract oversized functions: peer_actor/server_actor handle_message
  into per-message helpers, main() into init_logging/run_default_tui,
  download_selector and main_tui render into per-section helpers

Mechanical only, zero behavior change. Verified: clippy clean
(pedantic+nursery), fmt clean, 143 unit tests + 16 e2e tests against
soulfind pass, lint clean.

soulseek-rs-lib/src/utils/logger.rs

@@ -96,7 +96,9 @@ pub fn log(level: LogLevel, message: &str) {
             };
 
             let now = std::time::SystemTime::now();
-            let datetime = now.duration_since(std::time::UNIX_EPOCH).unwrap();
+            let datetime = now
+                .duration_since(std::time::UNIX_EPOCH)
+                .unwrap_or_default();
             let secs = datetime.as_secs();
             let subsec_millis = datetime.subsec_millis();
 

soulseek-rs-lib/src/utils/md5.rs

@@ -297,7 +297,6 @@ fn compute_md5_digest(mut v: Vec<u8>) -> String {
         let word_cc = word_c;
         let word_dd = word_d;
 
-        // execute round 1
         let result =
             round_one_operations(word_a, word_b, word_c, word_d, &table, &x);
         word_a = result[0];
@@ -305,7 +304,6 @@ fn compute_md5_digest(mut v: Vec<u8>) -> String {
         word_c = result[2];
         word_d = result[3];
 
-        // execute round 2
         let result =
             round_two_operations(word_a, word_b, word_c, word_d, &table, &x);
 
@@ -314,7 +312,6 @@ fn compute_md5_digest(mut v: Vec<u8>) -> String {
         word_c = result[2];
         word_d = result[3];
 
-        // execute round 3
         let result =
             round_three_operations(word_a, word_b, word_c, word_d, &table, &x);
         word_a = result[0];
@@ -322,7 +319,6 @@ fn compute_md5_digest(mut v: Vec<u8>) -> String {
         word_c = result[2];
         word_d = result[3];
 
-        // execute round 4
         let result =
             round_four_operations(word_a, word_b, word_c, word_d, &table, &x);
         word_a = result[0];

soulseek-rs-lib/src/utils/zlib.rs

@@ -184,17 +184,12 @@ impl HuffmanTree {
         let mut node = &mut self.root;
         for i in (0..n).rev() {
             let b = (codeword >> i) & 1;
-            if b != 0 {
-                if node.right.is_none() {
-                    node.right = Some(Box::new(Node::new()));
-                }
-                node = node.right.as_mut().unwrap();
+            let child = if b != 0 {
+                &mut node.right
             } else {
-                if node.left.is_none() {
-                    node.left = Some(Box::new(Node::new()));
-                }
-                node = node.left.as_mut().unwrap();
-            }
+                &mut node.left
+            };
+            node = child.get_or_insert_with(|| Box::new(Node::new()));
         }
         node.symbol = Some(symbol);
     }