Prepare for v3.0.0 release with changelog and semver updates

.env.example

@@ -1,5 +1,5 @@
 APP_NAME="Quantum PHP Framework"
-APP_VERSION=2.9.9
+APP_VERSION=3.0.0
 DB_DRIVER=mysql
 DB_HOST=localhost
 DB_NAME=

CHANGELOG.md

@@ -0,0 +1,14 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on Keep a Changelog and this project adheres to Semantic Versioning.
+
+## [3.0.0] - 2026-05-28
+
+### Changed
+- Upgraded downstream framework dependency from `quantum/framework` `dev-master` to stable `3.0.0`.
+- Updated `.env.example` default `APP_VERSION` from `2.9.9` to `3.0.0`.
+
+### Notes
+- This release aligns the downstream project with upstream `quantum/framework` `3.0.0`.

composer.json

@@ -6,7 +6,7 @@
     "type": "project",
     "require": {
         "php": "^7.4 || ^8.0",
-        "quantum/framework": "dev-master",
+        "quantum/framework": "^3.0.0",
         "fakerphp/faker": "^1.15",
         "bluemmb/faker-picsum-photos-provider": "^2.0",
         "ottaviano/faker-gravatar": "^0.3.0",