Initial commit: dynamic music & FX players

Continuous music players (DynamicSoundPlayer, 2D, 3D) with intensity-blended
layers, playlist queue, Loop, fade in/out, pause/resume. One-shot SFX players
(DynamicSoundFXPlayer, 2D, 3D) for overlapping triggers. All variants share
RefCounted core classes via duck-typed property access.

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

icon.svg.import

@@ -0,0 +1,43 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://b7i126kalykof"
+path="res://.godot/imported/icon.svg-9a86c2ed9bf8d44461ea973f38915c93.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://addons/gd-dynamic-sound/icon.svg"
+dest_files=["res://.godot/imported/icon.svg-9a86c2ed9bf8d44461ea973f38915c93.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
+svg/scale=1.0
+editor/scale_with_editor_scale=false
+editor/convert_colors_with_editor_theme=false