release: 4.5.9 release pipeline + defensive parsing

- scripts/release_gitea.mjs: --skip-build flag and auto-skip when
  artifacts for the version already exist on disk
- playwright in devDependencies; test:e2e* scripts call node directly
- loadConfig isPlainObject shape check + loadQueue sanitizes every
  entry incl. customClip/mergeGroup; stale status="downloading" is
  demoted to "pending" so the queue can actually be resumed

See docs/IMPROVEMENT_LOG.md (Cycle 2, 2026-05-03) for the dated
rationale and regression run.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "twitch-vod-manager",
-  "version": "4.5.8",
+  "version": "4.5.9",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "twitch-vod-manager",
-      "version": "4.5.8",
+      "version": "4.5.9",
       "license": "MIT",
       "dependencies": {
         "axios": "^1.6.0",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "twitch-vod-manager",
-  "version": "4.5.8",
+  "version": "4.5.9",
   "description": "Twitch VOD Manager - Download Twitch VODs easily",
   "main": "dist/main.js",
   "author": "xRangerDE",