Add Cargo dependency audit gates

.cargo/audit.toml

@@ -0,0 +1,21 @@
+[advisories]
+ignore = [
+    # Unmaintained transitive dependencies with no patched version.
+    "RUSTSEC-2020-0095", # difference via the release-only apple-codesign crate
+    "RUSTSEC-2024-0436", # paste via Iced's wgpu Metal backend
+    "RUSTSEC-2025-0134", # rustls-pemfile via apple-codesign's unused remote-signing stack
+    "RUSTSEC-2026-0192", # ttf-parser via Iced's text and SVG renderers
+    "RUSTSEC-2026-0206", # rustybuzz via Iced's SVG renderer
+
+    # No compatible upgrade exists; Cryoglyph does not call the affected LruCache::pop API.
+    "RUSTSEC-2026-0253",
+
+    # No patch exists; the release packager only creates ad-hoc signatures without RSA keys.
+    "RUSTSEC-2023-0071",
+]
+
+[output]
+deny = ["warnings"]
+format = "terminal"
+quiet = false
+show_tree = true