chore(release): prepare v0.13.0-beta (#489)

- Bump version 0.12.0-beta -> 0.13.0-beta (src/vocalinux/version.py)
- README: refresh "What's New" for v0.13.0-beta and bump comparison table
- docs/UPDATE.md: add v0.13.0-beta section and bump checkout example
- SECURITY.md: mark 0.13.x supported, 0.12.x unsupported
- docs/RELEASE_PROCESS.md: add v0.13.0-beta to version history
- web: bump package.json / package-lock.json / page.tsx schema + badge
- web changelog: add v0.13.0-beta entry and refresh dateModified

web/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "vocalinux-website",
-  "version": "0.12.0",
+  "version": "0.13.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "vocalinux-website",
-      "version": "0.12.0",
+      "version": "0.13.0",
       "dependencies": {
         "@types/node": "^20.14.10",
         "@types/react": "^18.3.3",