release: v0.7.13 — Developer-ID signed + notarized macOS

- bump version 0.7.12 -> 0.7.13 across package.json, Cargo.toml,
  tauri.conf.json, website version string, and version tests
- README: update both download tables + tag instructions to v0.7.13,
  add v0.7.13 changelog entry
- website: remove the sudo xattr quarantine hint (macOS is now signed +
  notarized), drop the copy-quarantine handler + macos-hint animation
  from landing.js, add v0.7.13 changelog entry

www/src/data/changelog.ts

@@ -5,6 +5,13 @@ export interface ChangelogEntry {
 }
 
 export const changelogEntries: ChangelogEntry[] = [
+  {
+    version: "0.7.13",
+    date: "2026-09-04",
+    highlights: [
+      "macOS is now Developer-ID signed and notarized — the app is properly code-signed with a Developer ID Application certificate and notarized by Apple, so macOS opens it without the Gatekeeper 'Open Anyway' prompt or the xattr quarantine workaround.",
+    ],
+  },
   {
     version: "0.7.12",
     date: "2026-09-01",