chore(lint): clean up clippy warnings across workspace

Auto-applied cargo clippy --fix across 11 files — needless return,
unnecessary cast, map_or simplification, repeat().take() → repeat_n(),
iter().any() → contains(), manual char comparison, lifetime elision,
push_str single-char, reference immediately dereferenced.

Also fixed three lints on file_storage.rs manually: two doc-list-item
overindentations, plus the same needless-return. Baseline main was
not clippy-clean with -D warnings before; after this pass one
needless_range_loop warning remains (live.rs:1089) that clippy's
suggested rewrite would make less readable — left for a dedicated
refactor session.

Build + workspace tests remain green (245 passing, 0 failing, 1
ignored).

crates/storage/src/file_storage.rs

@@ -2,11 +2,11 @@ use std::path::PathBuf;
 
 /// Resolve the per-user app data directory, following each OS's convention:
 ///
-/// - Windows: `%LOCALAPPDATA%\kon\`           e.g. `C:\Users\Jake\AppData\Local\kon`
+/// - Windows: `%LOCALAPPDATA%\kon\` — e.g. `C:\Users\Jake\AppData\Local\kon`
 /// - macOS:   `~/Library/Application Support/Kon/`
 /// - Linux:   `$XDG_DATA_HOME/kon` or `~/.local/share/kon` (XDG Base Directory),
-///            with a fallback to the legacy `~/.kon/` if it already exists, so
-///            existing installs keep working.
+///   with a fallback to the legacy `~/.kon/` if it already exists, so
+///   existing installs keep working.
 /// - Other Unix: `~/.kon/`
 ///
 /// TODO: Consolidate with `crates/transcription/src/model_manager.rs::dirs_path()`
@@ -45,7 +45,7 @@ pub fn app_data_dir() -> PathBuf {
                 return PathBuf::from(xdg).join("kon");
             }
         }
-        return PathBuf::from(home).join(".local").join("share").join("kon");
+        PathBuf::from(home).join(".local").join("share").join("kon")
     }
 
     #[cfg(not(any(target_os = "windows", target_os = "macos", target_os = "linux")))]