feat: add GSP customized install.php with port support, auto-admin, and ogp_ migration

Agent-Logs-Url: https://github.com/GameServerPanel/GSP/sessions/4b32e3c2-afec-458b-bf16-48e58045cc8b

Co-authored-by: iaretechnician <2749183+iaretechnician@users.noreply.github.com>

docs/GSP_INSTALLER.md

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+# GSP Installer – Differences from Original OGP `install.php`
+
+## Overview
+
+`install.php` in this repository is a customized installer for the
+**GSP (Game Server Panel)** maintained by WDS. It is based on the original
+OGP installer at
+<https://github.com/OpenGamePanel/OGP-Website/blob/master/install.php>
+but has been adapted for the GSP/WDS environment.
+
+---
+
+## Key differences
+
+### 1. Default table prefix: `gsp_`
+
+The original OGP installer defaults to `ogp_`. Our installer defaults to
+`gsp_` (the `$table_prefix` form field pre-fills with `gsp_`). You may
+change this during installation.
+
+### 2. Config file now includes `$db_port`
+
+The generated `includes/config.inc.php` includes a `$db_port` variable:
+
+```php
+$db_host="HOST";
+$db_port="3306";
+$db_user="USER";
+$db_pass="PASSWORD";
+$db_name="DATABASE";
+$table_prefix="gsp_";
+$db_type="mysql";
+```
+
+Existing config files that predate this installer and lack `$db_port`
+continue to work because the parameter defaults to `NULL` (MySQL default
+port 3306).
+
+### 3. MySQLi connection uses the port
+
+`includes/database_mysqli.php` – `OGPDatabaseMySQL::connect()` – now
+accepts an optional `$db_port` argument and passes it to `mysqli_connect()`:
+
+```php
+$this->link = mysqli_connect($db_host, $db_user, $db_pass, $db_name, $port);
+```
+
+`includes/helpers.php` – `createDatabaseConnection()` – likewise accepts
+and forwards `$db_port`.
+
+All panel entry points (`home.php`, `index.php`, `ogp_api.php`,
+`server_status.php`, `modules/billing/cron-shop.php`,
+`modules/billing/includes/panel_bridge.php`) pass
+`isset($db_port) ? $db_port : NULL` when calling
+`createDatabaseConnection()`.
+
+### 4. Default admin account created automatically
+
+After modules are installed, the installer automatically creates an `admin`
+account with password `admin` using the existing `OGPDatabaseMySQL::addUser()`
+method (which stores passwords as `MD5`). If an admin user already exists it
+is **not** duplicated.
+
+**Change the default password immediately after your first login.**
+
+### 5. No prerequisite checks
+
+Step 0 shows a welcome screen and language selector only. The original OGP
+installer checks for required PHP extensions, Pear, etc. GSP skips those
+checks because the deployment environment is pre-validated by our bootstrap
+scripts.
+
+### 6. All modules installed automatically
+
+Every directory found under `modules/` is installed via
+`install_module()`. Prerequisite failures for individual modules are treated
+as warnings (not hard failures) so that the overall installation succeeds
+even if optional dependencies are missing.
+
+### 7. `ogp_` → `gsp_` table migration (optional, safe)
+
+If the database already contains tables prefixed with `ogp_`:
+
+* For each `ogp_X` table, if the corresponding `gsp_X` table does **not**
+  exist, it is renamed to `gsp_X`.
+* If `gsp_X` already exists, the rename is skipped silently.
+* The installer never aborts due to pre-existing tables.
+
+This allows upgrading an existing OGP installation to GSP without losing data.
+
+### 8. Branding
+
+The installer title and default site settings reference **GSP – Game Server
+Panel** and **WDS** instead of "Open Game Panel".
+
+---
+
+## Running the installer
+
+1. Upload/deploy the panel files.
+2. Ensure `includes/config.inc.php` is writable (or does not exist yet).
+3. Open `https://yoursite/install.php` in a browser.
+4. Select your language and click **Next**.
+5. Enter database credentials and click **Next**.
+6. The installer writes config, migrates tables (if needed), installs
+   modules, and creates the default admin account.
+7. **Delete `install.php`** from the server after installation.
+8. Optionally `chmod 644 includes/config.inc.php` for security.
+
+---
+
+## Rollback
+
+* To re-run the installer, simply navigate to `install.php` again.
+* If the wrong prefix was chosen, edit `includes/config.inc.php` manually or
+  re-run `install.php`.
+* Renamed (`ogp_` → `gsp_`) tables can be manually renamed back with
+  `RENAME TABLE gsp_X TO ogp_X` in MySQL.