v1.0.1 - Configure your own Gitea instance

Use your own Gitea instance through the configuration file.

• Removed the deployment-specific fallback server address.
• GITEA_URL is now required; absent, empty or malformed URLs fail before API access.
• The example uses https://gitea.example.com and auto-detects the token account by default.
• Documented custom domains, ports and subdirectory installations such as /gitea.

Upgrade: ensure /etc/gitea-github-sync.conf contains your instance URL:

GITEA_URL='https://your-gitea.example.com'

Include a path prefix if your installation uses one. Do not append /api/v1.
Existing configurations with a valid GITEA_URL continue to work unchanged.

Validation: Bash syntax, ShellCheck and local tests for missing/invalid URLs
and authenticated requests to a configured host, port and path prefix.