fix: rename license files to fix GitHub license detection (#2024)

GitHub's licensee detection returns NOASSERTION because LICENSE.md
contains only a short markdown wrapper instead of actual license text.

Rename license files to match the pattern used by vis-network (which
is detected correctly):

* LICENSE.md → LICENSE (keeps the wrapper/index file)
* LICENSE.Apache-2.0.txt → LICENSE-APACHE-2.0
* LICENSE.MIT.txt → LICENSE-MIT

Update references in README.md and package snapshot test accordingly.

Closes #2024

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: r@l

LICENSE.md LICENSELICENSE.md renamed to LICENSE

@@ -3,7 +3,7 @@
 Copyright (c) 2014-2017 Almende B.V. and contributors
 Copyright (c) 2017-2019 vis.js contributors
 
-This work is dual-licensed under [Apache-2.0](./LICENSE.Apache-2.0.txt) and [MIT](./LICENSE.MIT.txt).
+This work is dual-licensed under [Apache-2.0](./LICENSE-APACHE-2.0) and [MIT](./LICENSE-MIT).
 You can choose between one of them if you use this work.
 
 `SPDX-License-Identifier: Apache-2.0 OR MIT`

LICENSE.Apache-2.0.txt LICENSE-APACHE-2.0LICENSE.Apache-2.0.txt renamed to LICENSE-APACHE-2.0

@@ -211,7 +211,7 @@ Support this project by becoming a sponsor. Your logo will show up here with a l
 Copyright (c) 2014-2017 Almende B.V. and contributors
 Copyright (c) 2017-2025 vis.js contributors
 
-This work is dual-licensed under [Apache-2.0](./LICENSE.Apache-2.0.txt) and [MIT](./LICENSE.MIT.txt).
+This work is dual-licensed under [Apache-2.0](./LICENSE-APACHE-2.0) and [MIT](./LICENSE-MIT).
 You can choose between one of them if you use this work.
 
 `SPDX-License-Identifier: Apache-2.0 OR MIT`

LICENSE.MIT.txt LICENSE-MITLICENSE.MIT.txt renamed to LICENSE-MIT

@@ -4,13 +4,13 @@ exports['Package Exported files 1'] = {
     "HISTORY.md": {
       "empty": false
     },
-    "LICENSE.Apache-2.0.txt": {
+    "LICENSE": {
       "empty": false
     },
-    "LICENSE.md": {
+    "LICENSE-APACHE-2.0": {
       "empty": false
     },
-    "LICENSE.MIT.txt": {
+    "LICENSE-MIT": {
       "empty": false
     },
     "README.md": {