Shuffle floor colors each round, keep eliminated players out of spectator mode, add optional match music

README.md

@@ -114,6 +114,13 @@ work fine from console.
   configured palette) across the whole region and serializes it into the arena's yml file
   (`generated-layout`) so it can be restored exactly, every round, without re-scanning or
   re-randomizing the world.
+- By default the *positions* from that saved layout are reused every round, but which color
+  sits at which position is reshuffled (`floor.shuffle-each-round: true` in `config.yml`) at
+  the start of the match and before every round's restore — so the board isn't a static,
+  memorizable pattern for the whole game. The shuffle only permutes materials in memory; the
+  saved `generated-layout` itself is never modified, so a restart or another `/bp generate`
+  still starts from the original. Set `shuffle-each-round: false` to always restore the exact
+  saved layout unchanged instead.
 
 ### Billboards
 
@@ -149,7 +156,10 @@ nothing leaks.
   target block is placed in your hotbar (slot 9) as a visual reminder. A boss bar (if
   enabled) shows the remaining time as a shrinking progress bar.
 - Get eliminated by not standing on the target color when the floor clears, or by falling
-  off entirely. Eliminated players become spectators at the configured spectator location.
+  off entirely. Eliminated players are teleported to the configured spectator location and
+  marked as spectators for gameplay purposes (no damage, can't interfere), but stay in
+  adventure mode rather than true spectator mode — no noclip/flight, just watching from where
+  they landed.
 - Last player standing wins; rewards, stats and celebration effects (fireworks, titles,
   sounds) fire automatically.
 - **Solo play**: if a match starts with only one player (e.g. `min-players: 1` for testing),
@@ -166,14 +176,34 @@ nothing leaks.
   future/optional batched floor operations — round-end removal and each round's floor reset
   are always instantaneous, all blocks at once, by design),
   `defaults.*` (used only when `/bp create` seeds a new arena), `default-floor-materials`
-  (the full 16-color concrete palette by default), `rewards.winner.commands`, and
-  `integrations.placeholderapi`.
+  (the full 16-color concrete palette by default), `floor.shuffle-each-round`, `music.*`
+  (see "Music" below), `rewards.winner.commands`, and `integrations.placeholderapi`.
 - **`messages.yml`** — every user-facing string, in [MiniMessage](https://docs.advntr.dev/minimessage/format.html)
   format (Adventure, bundled with Paper). Placeholders like `%player%`, `%arena%`, `%round%`,
   `%time%`, `%color%` are substituted per-message.
 - **`arenas/<name>.yml`** — one file per arena; a broken file only disables that one arena
   (the rest still load) and the error is logged.
 
+### Music
+
+Optional background music for the duration of a match, off by default:
+
+```yaml
+music:
+  enabled: true
+  track: MUSIC_DISC_PIGSTEP
+  volume: 1.0
+```
+
+`track` is any Bukkit `Sound` enum name that's actually a track (one of the `MUSIC_DISC_*`
+sounds, or a `MUSIC_*` ambient track) — invalid names are logged and skipped, never crash the
+plugin. It plays on the client's dedicated **Music** volume slider (via `SoundCategory.MUSIC`),
+separately from sound effects, starting when a match begins. It's paused the instant the floor
+wipes each round and resumed once the floor has fully reset for the next round. Note this is a
+stop/replay-from-the-start rather than a true mid-track pause/resume — vanilla Minecraft's sound
+API has no seek/resume-from-position, so each "resume" restarts the track from the beginning.
+It's stopped entirely at match end, arena disable, or plugin shutdown.
+
 ### Reload behavior
 
 `/blockparty reload` re-reads `config.yml`, `messages.yml`, and every arena file. Arenas