Update repository URLs to Gitea

- Change all URLs from github.com to opensource.rogarithm.net
- Update Docker image references to local build (php-security-linter:latest)
- Fix Gitea Issues URL in CONTRIBUTING.md

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

composer.json

@@ -15,15 +15,15 @@
         "vulnerability",
         "sast"
     ],
-    "homepage": "https://github.com/security-linter/php-laravel",
+    "homepage": "https://opensource.rogarithm.net/rogarithm/php-security-linter",
     "support": {
-        "issues": "https://github.com/security-linter/php-laravel/issues",
-        "source": "https://github.com/security-linter/php-laravel"
+        "issues": "https://opensource.rogarithm.net/rogarithm/php-security-linter/issues",
+        "source": "https://opensource.rogarithm.net/rogarithm/php-security-linter"
     },
     "authors": [
         {
             "name": "Security Linter Contributors",
-            "homepage": "https://github.com/security-linter/php-laravel/contributors"
+            "homepage": "https://opensource.rogarithm.net/rogarithm/php-security-linter/contributors"
         }
     ],
     "autoload": {