Add PHPStan and other quality checks

Similar to FreshRSS core
Contributes to https://github.com/FreshRSS/Extensions/issues/184

xExtension-TTRSS_API/README.md

@@ -6,6 +6,6 @@ Note the API is NOT FULLY SUPPORTED YET!
 
 Please be sure to enable API in the configuration and set an API password on your profile.
 
-URL to use is something like http://rss.example.com/api/ttrss.php or http://example.com/freshrss/p/api/ttrss.php.
+URL to use is something like <http://rss.example.com/api/ttrss.php> or <http://example.com/freshrss/p/api/ttrss.php>.
 
 To use it, upload this directory in your `./extensions` directory and enable it on the extension panel in FreshRSS.

xExtension-TTRSS_API/extension.php

@@ -1,11 +1,12 @@
 <?php
-
 declare(strict_types=1);
 
 class TTRSS_APIExtension extends Minz_Extension {
 	public function init() {
-		$this->registerHook('post_update',
-		                    array($this, 'postUpdateHook'));
+		$this->registerHook(
+			'post_update',
+			array($this, 'postUpdateHook')
+		);
 	}
 
 	public function install() {

xExtension-TTRSS_API/ttrss.php

@@ -339,7 +339,7 @@ class FreshAPI_TTRSS {
 
 			if ($show_excerpt) {
 				// @todo add a facultative max char in content method to get
-				// an exerpt.
+				// an excerpt.
 				$line['excerpt'] = $item->content();
 			}