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/weapons/dryfire1.wav.import

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+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://bkuqkytgyiqoc"
+path="res://.godot/imported/dryfire1.wav-a0ce0b345f70cf8c349f33366ea96915.sample"
+
+[deps]
+
+source_file="res://assets/audio/weapons/dryfire1.wav"
+dest_files=["res://.godot/imported/dryfire1.wav-a0ce0b345f70cf8c349f33366ea96915.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/weapons/explode3.wav.import

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+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://d2tbx2yh7bsgb"
+path="res://.godot/imported/explode3.wav-3dba11140b272f7d09f0a32dae9c68f4.sample"
+
+[deps]
+
+source_file="res://assets/audio/weapons/explode3.wav"
+dest_files=["res://.godot/imported/explode3.wav-3dba11140b272f7d09f0a32dae9c68f4.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/weapons/explode4.wav.import

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+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://7rp6ypy5qkxo"
+path="res://.godot/imported/explode4.wav-2a1fd2def1be7f87e2d4170c7935734e.sample"
+
+[deps]
+
+source_file="res://assets/audio/weapons/explode4.wav"
+dest_files=["res://.godot/imported/explode4.wav-2a1fd2def1be7f87e2d4170c7935734e.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/weapons/explode5.wav.import

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+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://cmbo466uy2w44"
+path="res://.godot/imported/explode5.wav-f37b7d55a94ca74c637137d08c0efc5a.sample"
+
+[deps]
+
+source_file="res://assets/audio/weapons/explode5.wav"
+dest_files=["res://.godot/imported/explode5.wav-f37b7d55a94ca74c637137d08c0efc5a.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/weapons/hks1.wav.import

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+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://eu4mpcdrhujg"
+path="res://.godot/imported/hks1.wav-5afc7788d247a6e2ecdee212682213f3.sample"
+
+[deps]
+
+source_file="res://assets/audio/weapons/hks1.wav"
+dest_files=["res://.godot/imported/hks1.wav-5afc7788d247a6e2ecdee212682213f3.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/weapons/hks2.wav.import

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+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://ba2p4vv66pxbo"
+path="res://.godot/imported/hks2.wav-a8fa00ea683bacaa73ed3971af49ec46.sample"
+
+[deps]
+
+source_file="res://assets/audio/weapons/hks2.wav"
+dest_files=["res://.godot/imported/hks2.wav-a8fa00ea683bacaa73ed3971af49ec46.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/weapons/hks3.wav.import

@@ -0,0 +1,24 @@
+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://cldvtw12686n6"
+path="res://.godot/imported/hks3.wav-6d4c5e98aa75a598bbaeb4d3ae9762fa.sample"
+
+[deps]
+
+source_file="res://assets/audio/weapons/hks3.wav"
+dest_files=["res://.godot/imported/hks3.wav-6d4c5e98aa75a598bbaeb4d3ae9762fa.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