release: 5.0.0-alpha.2 - OAuth foundation (storage layer)

Plan 03 abgeschlossen.
- schema-v5.ts: oauth_accounts table (provider, twitch_user_id, encrypted_*_token, ...)
- src/main/infra/secure-storage.ts: SecureStorage interface + Memory + Electron impls
- src/main/domain/token-store.ts: provider-agnostic CRUD on oauth_accounts
- 126 unit tests (vorher 106, +20 fuer schema + secure-storage + token-store)
- npm run test:e2e:release gruen

Twitch OAuth Flow itself (Authorization Code + PKCE via system browser
or embedded BrowserWindow) is deferred to Plan 03b — goal.md proposed
Device Code Flow which Twitch does not support.

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

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "twitch-vod-manager",
-  "version": "5.0.0-alpha.1",
+  "version": "5.0.0-alpha.2",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "twitch-vod-manager",
-      "version": "5.0.0-alpha.1",
+      "version": "5.0.0-alpha.2",
       "license": "MIT",
       "dependencies": {
         "axios": "^1.6.0",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "twitch-vod-manager",
-  "version": "5.0.0-alpha.1",
+  "version": "5.0.0-alpha.2",
   "description": "Twitch VOD Manager - Download Twitch VODs easily",
   "main": "dist/main.js",
   "author": "xRangerDE",