Add recently played tracking with shows and broadcasts

- sql/schema.sql: shows, broadcasts and played_tracks tables, seeded
  with the five shows
- cli/poll_icecast.php: cron-run poller that records broadcasts and
  tracks every 15 seconds while streaming; tracks are cleared ten
  minutes after a broadcast ends
- cli/set_show.php: queue the next show, or assign one to the live
  broadcast
- recently_played.php: track history rows for live.php, with album art
  and album title linking to Last.fm
- live.php: recently played list, show name in heading, and per-show
  header background
- includes/icecast.php: Icecast parsing, album art and Last.fm helpers
  shared by now_playing.php and the poller
- includes/db.php: use UTC for the database session

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cli/poll_icecast.php

@@ -0,0 +1,29 @@
+<?php
+// Polls Icecast and records track history. Run from cron once a minute; each run polls
+// four times, 15 seconds apart:
+//   * * * * * php /path/to/rfe/cli/poll_icecast.php
+
+if (PHP_SAPI !== 'cli') {
+    http_response_code(403);
+    exit;
+}
+
+require __DIR__ . '/../includes/db.php';
+require __DIR__ . '/../includes/broadcasts.php';
+
+// Skip this run if the previous one is still going
+$lock = fopen(sys_get_temp_dir() . '/rfe_poll_icecast.lock', 'c');
+if (!flock($lock, LOCK_EX | LOCK_NB)) exit;
+
+for ($i = 0; $i < 4; $i++) {
+    if ($i > 0) sleep(15);
+
+    $track = fetchCurrentTrack();
+    if ($track === false) continue; // Status API unreachable; don't treat it as the stream ending
+
+    try {
+        recordPoll(getDB(), $track);
+    } catch (Throwable $e) {
+        fwrite(STDERR, date('c') . ' ' . $e->getMessage() . "\n");
+    }
+}