Self-hosted auto-updates from Gitea via PUC + proprietary licence

Vendors YahnisElsts/plugin-update-checker v5.7 under vendor/ and wires
it to poll updates.json on the repo main branch. WP surfaces new
versions via Dashboard → Updates on its normal twice-daily cadence.

PUC is vendored (not a submodule) so Gitea's archive/main.zip — the
download target — includes it.

Also relicenses from GPL-2.0-or-later to a proprietary licence granting
use only to authorised sites, with all other rights reserved. Plugin
URI + Author URI switched from the placeholder github.com URL to the
canonical Gitea repo.

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

vendor/plugin-update-checker/.editorconfig

@@ -0,0 +1,15 @@
+[*]
+charset=utf-8
+end_of_line=lf
+insert_final_newline=false
+indent_style=tab
+tab_width=4
+
+[{phpunit.xml.dist,*.jhm,*.xslt,*.xul,*.rng,*.xsl,*.xsd,*.ant,*.tld,*.fxml,*.jrxml,*.xml,*.jnlp,*.wsdl}]
+indent_style=space
+indent_size=4
+
+[*.svg]
+indent_style=space
+indent_size=4
+