Fix 29 audit findings across all severity tiers

Critical: fix unsquashfs arg order, quote Exec paths with spaces,
fix compare_versions antisymmetry, chunk-based signature detection,
bounded ELF header reads.

High: handle NULL CVE severity, prevent pipe deadlock in inspector,
fix glob_match edge case, fix backup archive path collisions, async
crash detection with stderr capture.

Medium: gate scan on auto-scan setting, fix window size persistence,
fix announce() for Stack containers, claim lightbox gesture, use
serde_json for CLI output, remove dead CSS @media blocks, add
detail-tab persistence, remove invalid metainfo categories, byte-level
fuse signature search.

Low: tighten Wayland env var detection, ELF magic validation,
timeout for update info extraction, quoted arg parsing, stop watcher
timer on window destroy, GSettings choices/range constraints, remove
unused CSS classes, define status-ok/status-attention CSS.

src/core/watcher.rs

@@ -8,7 +8,7 @@ use notify::{Config, Event, EventKind, RecommendedWatcher, RecursiveMode, Watche
 #[derive(Debug, Clone)]
 pub enum WatchEvent {
     /// One or more AppImage files were created, modified, or deleted.
-    Changed(#[allow(dead_code)] Vec<PathBuf>),
+    Changed(Vec<PathBuf>),
 }
 
 /// Start watching the given directories for AppImage file changes.