Move and activate CODEOWNERS (#632)

Moves CODEOWNERS from the repo root to .github/ and replaces the
fully-commented-out file with an active configuration using
@react-ui-org/maintainers as the default team.

Author: adamkudrna

.github/CODEOWNERS

@@ -0,0 +1,23 @@
+# Default owners for code review
+*                           @react-ui-org/maintainers
+
+# Protect against unauthorized changes
+/.github/CODEOWNERS         @react-ui-org/maintainers
+
+# Soft gates — any team member can review, but relevant expert is notified
+
+# Infrastructure & build tooling
+/docker/                    @bedrich-schindler @mbohal @react-ui-org/maintainers
+/docker-compose.yml         @bedrich-schindler @mbohal @react-ui-org/maintainers
+/webpack.config.babel.js    @bedrich-schindler @mbohal @react-ui-org/maintainers
+/babel.config.js            @bedrich-schindler @mbohal @react-ui-org/maintainers
+/jest.config.js             @bedrich-schindler @mbohal @react-ui-org/maintainers
+/.eslintrc                  @bedrich-schindler @mbohal @react-ui-org/maintainers
+
+# Docs, styles & style tooling
+*.md                        @adamkudrna @react-ui-org/maintainers
+/postcss.config.js          @adamkudrna @react-ui-org/maintainers
+/src/docs/                  @adamkudrna @react-ui-org/maintainers
+/src/styles/                @adamkudrna @react-ui-org/maintainers
+/src/theme.scss             @adamkudrna @react-ui-org/maintainers
+/stylelint.config.js        @adamkudrna @react-ui-org/maintainers

.npmignore

@@ -18,7 +18,6 @@
 .gitignore
 .markdownlint.jsonc
 babel.config.js
-CODEOWNERS
 docker-compose.yml
 jest.config.js
 mkdocs.yml