tools: add update_gitea_releases.py and release-notes snippets

One-shot script to backfill Gitea release bodies for existing releases
using the Gitea API. Reads per-version Markdown files from
tools/release-notes/ and PATCHes each release body.
Includes README.md in tools/release-notes/ explaining usage.

tools/release-notes/v2.2.0.md

@@ -0,0 +1,11 @@
+### Added
+- Linux MinGW-w64 cross-build support in `build_plugin.py` via `--host linux`
+- `tools/linux/build_plugin_linux.py` for standalone Linux builds
+- Color output and progress spinner in all legacy build scripts
+
+### Changed
+- `build_plugin.py` now supports both Windows (MSBuild) and Linux (MinGW-w64) targets
+- Windows build-script f-string fixes
+
+---
+_Repository primario: vedi link Gitea nel README. Il mirror GitHub è generato automaticamente._