add build, DMG creation scripts, CI/CD workflows

- build-bundle.sh: regenerates Info.plist with KLInfo entries for all 4
  layout versions, sets CalVer bundle version, validates plists
- create-dmg.sh: packages bundle into a DMG with drag-and-drop symlink
  to /Library/Keyboard Layouts/
- release.yml: GitHub Actions workflow that validates, builds, creates DMG,
  publishes GitHub Release on CalVer tag push
- validate.yml: CI validation on push/PR for layout and script changes
- Info.plist now declares all 4 layouts (was only v2.0)

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

EurKey-macOS.bundle/Contents/Info.plist

@@ -7,7 +7,40 @@
 	<key>CFBundleName</key>
 	<string>EurKEY-macOS</string>
 	<key>CFBundleVersion</key>
-	<string></string>
+	<string>2026.03.03</string>
+	<key>KLInfo_EurKEY v1.2</key>
+	<dict>
+		<key>TICapsLockLanguageSwitchCapable</key>
+		<false/>
+		<key>TISIconIsTemplate</key>
+		<true/>
+		<key>TISInputSourceID</key>
+		<string>de.felixfoertsch.keyboardlayout.EurKEY-macOS.eurkeyv1.2</string>
+		<key>TISIntendedLanguage</key>
+		<string>en</string>
+	</dict>
+	<key>KLInfo_EurKEY v1.3</key>
+	<dict>
+		<key>TICapsLockLanguageSwitchCapable</key>
+		<false/>
+		<key>TISIconIsTemplate</key>
+		<true/>
+		<key>TISInputSourceID</key>
+		<string>de.felixfoertsch.keyboardlayout.EurKEY-macOS.eurkeyv1.3</string>
+		<key>TISIntendedLanguage</key>
+		<string>en</string>
+	</dict>
+	<key>KLInfo_EurKEY v1.4</key>
+	<dict>
+		<key>TICapsLockLanguageSwitchCapable</key>
+		<false/>
+		<key>TISIconIsTemplate</key>
+		<true/>
+		<key>TISInputSourceID</key>
+		<string>de.felixfoertsch.keyboardlayout.EurKEY-macOS.eurkeyv1.4</string>
+		<key>TISIntendedLanguage</key>
+		<string>en</string>
+	</dict>
 	<key>KLInfo_EurKEY v2.0</key>
 	<dict>
 		<key>TICapsLockLanguageSwitchCapable</key>