Add industrial metal soundtrack with seamless loop

- assets/audio/music/zombie_industrial_loop.ogg: 57.60 s Ogg Vorbis loop
  generated locally with YuE2-3B on the Tesla V100 (score written for this
  track; vocals removed with HTDemucs). The loop is spliced at the track's
  structural repeat with a 0.6 s crossfade: measured seam dip <= 1.6 dB.
- scripts/main.gd: "Music" AudioStreamPlayer at -11 dB, started at boot on
  desktop and on the start click on Web (browser autoplay policy). It forces
  stream.loop at runtime because the Web staging step re-imports the OGG with
  loop=false.
- tools/test_music.gd: soundtrack test (loop, length, volume, playback,
  still playing after player death).
- docs/MUSIC.md: source, loop construction, verification, licence.
- docs/WEB-DEPLOY.md: release ab6054111f5919a8 notes.

Initial commit of the project.

assets/audio/player/pl_metal1.wav.import

@@ -0,0 +1,24 @@
+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://xyc5cwgyhfms"
+path="res://.godot/imported/pl_metal1.wav-42fb8eebd82a46db937bb26761e30ef3.sample"
+
+[deps]
+
+source_file="res://assets/audio/player/pl_metal1.wav"
+dest_files=["res://.godot/imported/pl_metal1.wav-42fb8eebd82a46db937bb26761e30ef3.sample"]
+
+[params]
+
+force/8_bit=false
+force/mono=false
+force/max_rate=false
+force/max_rate_hz=44100
+edit/trim=false
+edit/normalize=false
+edit/loop_mode=0
+edit/loop_begin=0
+edit/loop_end=-1
+compress/mode=2

assets/audio/player/pl_metal2.wav.import

@@ -0,0 +1,24 @@
+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://ho1s43gk3hh7"
+path="res://.godot/imported/pl_metal2.wav-68c295c4e5934b39639453eb4ac7bb86.sample"
+
+[deps]
+
+source_file="res://assets/audio/player/pl_metal2.wav"
+dest_files=["res://.godot/imported/pl_metal2.wav-68c295c4e5934b39639453eb4ac7bb86.sample"]
+
+[params]
+
+force/8_bit=false
+force/mono=false
+force/max_rate=false
+force/max_rate_hz=44100
+edit/trim=false
+edit/normalize=false
+edit/loop_mode=0
+edit/loop_begin=0
+edit/loop_end=-1
+compress/mode=2

assets/audio/player/pl_metal3.wav.import

@@ -0,0 +1,24 @@
+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://b4p7jku5hr3m5"
+path="res://.godot/imported/pl_metal3.wav-b7957637b584240fd4fbf20022deda4f.sample"
+
+[deps]
+
+source_file="res://assets/audio/player/pl_metal3.wav"
+dest_files=["res://.godot/imported/pl_metal3.wav-b7957637b584240fd4fbf20022deda4f.sample"]
+
+[params]
+
+force/8_bit=false
+force/mono=false
+force/max_rate=false
+force/max_rate_hz=44100
+edit/trim=false
+edit/normalize=false
+edit/loop_mode=0
+edit/loop_begin=0
+edit/loop_end=-1
+compress/mode=2

assets/audio/player/pl_metal4.wav.import

@@ -0,0 +1,24 @@
+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://6rqyer6de744"
+path="res://.godot/imported/pl_metal4.wav-75e3af6a3e59541fba589ed0077615b3.sample"
+
+[deps]
+
+source_file="res://assets/audio/player/pl_metal4.wav"
+dest_files=["res://.godot/imported/pl_metal4.wav-75e3af6a3e59541fba589ed0077615b3.sample"]
+
+[params]
+
+force/8_bit=false
+force/mono=false
+force/max_rate=false
+force/max_rate_hz=44100
+edit/trim=false
+edit/normalize=false
+edit/loop_mode=0
+edit/loop_begin=0
+edit/loop_end=-1
+compress/mode=2

assets/audio/player/pl_pain7.wav.import

@@ -0,0 +1,24 @@
+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://cgj8qrq5b8ek1"
+path="res://.godot/imported/pl_pain7.wav-9b92e039c95d7d9ed3bce71138d0d840.sample"
+
+[deps]
+
+source_file="res://assets/audio/player/pl_pain7.wav"
+dest_files=["res://.godot/imported/pl_pain7.wav-9b92e039c95d7d9ed3bce71138d0d840.sample"]
+
+[params]
+
+force/8_bit=false
+force/mono=false
+force/max_rate=false
+force/max_rate_hz=44100
+edit/trim=false
+edit/normalize=false
+edit/loop_mode=0
+edit/loop_begin=0
+edit/loop_end=-1
+compress/mode=2