Modernize Select2 integration and fix popover page jumping

- Upgraded Select2 from bundled v3.4.4 (2013) to v4.x peer dependency
- Removed legacy Select2 v3.x bundled files from lib directory
- Updated Select2 input to use v4.x API (events, AJAX, templates)
- Fixed Bootstrap 5 popover page jumping issue with multi-timeout scroll restoration
- Added comprehensive migration documentation in README-select2-upgrade.md
- Rebuilt all distribution files with updated source code

Breaking Changes:
- Select2 now requires separate installation as peer dependency
- AJAX configuration updated for v4.x format
- Event names changed (select2:select vs select2-loaded)
- Template functions renamed (templateResult vs formatResult)

package-lock.json

@@ -1,11 +1,11 @@
 {
-  "name": "@24unix/x-editable",
+  "name": "x-editable-bs5",
   "version": "1.5.2",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
-      "name": "@24unix/x-editable",
+      "name": "x-editable-bs5",
       "version": "1.5.2",
       "dependencies": {
         "bootstrap": "^5.3.3",
@@ -30,6 +30,9 @@
         "grunt-contrib-uglify": "^5.2.2",
         "style-loader": "^4.0.0",
         "webpack-cli": "^6.0.1"
+      },
+      "peerDependencies": {
+        "select2": "^4.0.0"
       }
     },
     "node_modules/@babel/code-frame": {
@@ -4424,6 +4427,13 @@
         "url": "https://opencollective.com/webpack"
       }
     },
+    "node_modules/select2": {
+      "version": "4.0.13",
+      "resolved": "https://registry.npmjs.org/select2/-/select2-4.0.13.tgz",
+      "integrity": "sha512-1JeB87s6oN/TDxQQYCvS5EFoQyvV6eYMZZ0AeA4tdFDYWN3BAGZ8npr17UBFddU0lgAt3H0yjX3X6/ekOj1yjw==",
+      "license": "MIT",
+      "peer": true
+    },
     "node_modules/semver": {
       "version": "7.7.1",
       "resolved": "https://registry.npmjs.org/semver/-/semver-7.7.1.tgz",