Add user maintenance CLI (#9)

- Add CLI infrastructure
- Add user to index page query
- Strip tags from title
- Move item parsing to FeedItem

src/cli-start.php

@@ -0,0 +1,26 @@
+<?php
+require 'app-config.php';
+
+if (php_sapi_name() != 'cli') {
+    http_response_code(404);
+    die('Not Found');
+}
+
+/**
+ * Print a line with a newline character at the end (printf + newline = printfn; surprised this isn't built in!)
+ *
+ * @param string $format The format string
+ * @param mixed ...$values The values for the placeholders in the string
+ */
+function printfn(string $format, mixed ...$values): void {
+    printf($format . PHP_EOL, ...$values);
+}
+
+/**
+ * Display a title for a CLI run
+ *
+ * @param string $title The title to display on the command line
+ */
+function cli_title(string $title): void {
+    printfn("$title | Feed Reader Central v%s" . PHP_EOL, FRC_VERSION);
+}