ci: add GitHub Actions workflows with semantic-release auto-versioning

chore: fix all 702 clippy warnings across codebase
- auto-fix 475 via cargo clippy --fix
- fix remaining 227 manually: uninlined_format_args, redundant_closure, match_same_arms,
  underscore_binding, format_push_string, items_after_statements, needless_pass_by_value,
  clone_on_copy, case_sensitive_extension, single_match/let-else, write_with_newline,
  and other clippy lints

src/model/session.rs

@@ -89,7 +89,7 @@ impl Session {
         if id.contains('/') || id.contains('\\') || id.contains("..") {
             return Err(std::io::Error::new(
                 std::io::ErrorKind::InvalidInput,
-                format!("invalid session id '{}': must not contain path separators", id),
+                format!("invalid session id '{id}': must not contain path separators"),
             ));
         }
         let path = base_dir.join("sessions").join(id).join("session.json");
@@ -108,12 +108,9 @@ impl Session {
     /// contains no valid sessions.
     pub fn list(base_dir: &Path) -> Vec<Self> {
         let sessions_dir = base_dir.join("sessions");
-        let entries = match std::fs::read_dir(&sessions_dir) {
-            Ok(e) => e,
-            Err(_) => return Vec::new(),
-        };
+        let Ok(entries) = std::fs::read_dir(&sessions_dir) else { return Vec::new() };
         entries
-            .filter_map(|e| e.ok())
+            .filter_map(std::result::Result::ok)
             .filter(|e| e.path().is_dir())
             .filter_map(|e| {
                 let id = e.file_name().to_string_lossy().to_string();