feat(0.5.0): track history + favourites with four search providers

Quietly log every track that scrolls past the player to a per-user
history (capped 500). A star button promotes the good ones to a
separate Favourites tab that doesn't age out. Each row has four
search-provider deep links so you can find the track on whichever
service you use.

Storage
  Two new user_meta keys (separate from radio_state so frequent
  inserts don't churn the player-state blob):
    - radio_history    — capped FIFO of last 500 played tracks
    - radio_favourites — uncapped user-starred list

New page: Radio → History
  - History tab: capped FIFO list, newest first.
  - Favourites tab: starred tracks (uncapped).
  - Each row: when (relative + full timestamp on hover) / station /
    artist — title / four search links / favourite-star toggle.
  - Filter by artist/title (live, client-side) + by station (dropdown).
  - Clear history button (favourites preserved).
  - Search providers: Spotify, YouTube, Apple Music, Bandcamp.
    Deep-link URLs only — no API keys, no third-party JS.

Auto-logging during playback
  fetchTrack (existing 30s SomaFM poll loop) now hands new tracks to
  logTrackIfNew → POST to wp_ajax_radio_log_track. Dedup client-side
  (lastLoggedSig) AND server-side (against last entry in user_meta).
  Junk filtered server-side: (unknown) artist, missing artist/title.

New AJAX endpoints
  - radio_log_track          (nonce radio_save_state — player pages)
  - radio_toggle_favourite   (nonce radio_history — history page only)
  - radio_clear_history      (nonce radio_history — history page only)

Files
  - radio.php (version, require new include, submenu page, asset
    enqueue hook adds radio_page_radio-history, three AJAX endpoints,
    three new localized strings)
  - inc/history.php (NEW — storage helpers + admin page renderer)
  - assets/css/radio.css (history table, toolbar, search-link pills,
    favourite star, dark-theme overrides)
  - assets/js/radio.js (logTrackIfNew wired into fetchTrack;
    bindHistoryPage handles filter/favourite/clear)
  - inc/about.php (history entry)
  - CHANGELOG.md (full entry)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -9,6 +9,41 @@ Format: [Keep a Changelog 1.1.0](https://keepachangelog.com/en/1.1.0/) — versi
 
 ---
 
+## [0.5.0] — 2026-05-29 — Track history + favourites
+
+SomaFM plays deep cuts you'll never hear again. v0.5.0 quietly logs every track that scrolls past so you can find it again later — and a star button keeps the ones worth keeping forever.
+
+### Added — `Radio → History` admin page (per-user)
+- **History tab** — capped FIFO list of the last 500 played tracks. Each row shows when (relative time, full timestamp on hover), station, *artist — title*, four search links, and a favourite-star toggle.
+- **Favourites tab** — uncapped list of starred tracks. Same row layout. Survives even when the history rolls over.
+- **Filter** by artist/title (live, client-side) and by station (dropdown). **Clear history** button on the History tab — favourites preserved.
+- **Four search providers** per row, brand-tinted on hover: **Spotify** (green), **YouTube** (red), **Apple Music** (pink), **Bandcamp** (teal). Deep-link search URLs only — no API keys, no third-party JS.
+- Empty-state messages on both tabs.
+
+### Added — automatic logging during playback
+- `fetchTrack` (the existing 30s SomaFM polling loop) now hands every new track to a new `logTrackIfNew` helper that POSTs it to `wp_ajax_radio_log_track`.
+- **Dedup**: client-side via `lastLoggedSig` so the 30s polling doesn't re-log the same song; server-side against the last entry in user_meta as belt-and-braces.
+- **Junk filtering**: `(unknown)` artists and entries missing artist *or* title are dropped server-side in `radio_sanitize_entry`.
+
+### Added — per-user storage
+- Two new `user_meta` keys, separate from `radio_state` so frequent track inserts don't churn the player-state blob:
+  - `radio_history` — capped at **500 entries** (~50–80 KB max).
+  - `radio_favourites` — uncapped, expected to stay small (user-curated).
+
+### Added — three new AJAX endpoints
+- `wp_ajax_radio_log_track` — append a track (nonce: `radio_save_state`; player-page only).
+- `wp_ajax_radio_toggle_favourite` — toggle a track in favourites (nonce: `radio_history`; History-page only).
+- `wp_ajax_radio_clear_history` — clear the history list (nonce: `radio_history`; History-page only). Favourites untouched.
+
+### Notes
+- Per-user — nothing is shared, nothing leaves the site. Just your own listening history on your own WP account.
+- **No PII concern** — entries are public station/artist/title strings from SomaFM's own JSON.
+- Search-link UI tints toward each provider's brand colour on hover only — keeps the row visually calm in the default state.
+
+**Files changed:** `radio.php` (version, require, submenu, asset enqueue hook, three AJAX endpoints, three new localized strings), **new** `inc/history.php` (storage helpers + page renderer), `assets/css/radio.css` (history-page table, toolbar, search-link pills, favourite star, dark-theme overrides), `assets/js/radio.js` (`logTrackIfNew` wired into `fetchTrack`; `bindHistoryPage` for filter/favourite/clear), `inc/about.php` (history entry).
+
+---
+
 ## [0.4.0] — 2026-05-29 — Now-playing indicator: dancing bars + Web Audio visualizer
 
 A small visual that instantly says *"this is playing right now."* Two layers — a reliable CSS-only indicator that always works, and a progressive Web Audio upgrade that draws actual frequency data when the browser allows.