feat: standalone ReleaseUpdater library v1.1.0

Promoted from DIYStickyNotes/lib/ReleaseUpdater (byte-identical src) into a
reusable Gitea library. Adds LICENSE, .gitignore, library.properties,
keywords.txt and carries the ReleaseUpdaterCore native unit test for
downstream reuse.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

library.json

@@ -0,0 +1,12 @@
+{
+  "name": "ReleaseUpdater",
+  "version": "1.1.0",
+  "description": "Self-update an ESP32 from GitHub/Gitea releases: version compare, asset selection, HTTPUpdate flashing, and an optional background service loop with idle-gate and UI/TLS hooks.",
+  "keywords": ["esp32", "ota", "github", "gitea", "release", "self-update"],
+  "authors": [{ "name": "xPablo.cz", "url": "https://git.xpablo.cz/xPablo.cz" }],
+  "license": "MIT",
+  "frameworks": "arduino",
+  "platforms": ["espressif32"],
+  "dependencies": [{ "name": "ArduinoJson", "version": "^7.0.0" }],
+  "build": { "libArchive": false }
+}