Quaternius weapons, input fixes, sound & path fixes

- Added 6 Quaternius weapon models (Pistol, Revolver, Rifle, Shotgun, P90, SniperRifle)
- Created weapon resource files with balanced stats
- Wired Pistol + Rifle into player.tscn replacing Kenney blasters
- Fixed WASD input (matched input map action names)
- Fixed Escape key toggles mouse capture
- Added Audio autoload singleton
- Fixed broken sound asset paths across all scripts
- Fixed all scene ext_resource text paths (nested under assets/kenney-fps/)
- Fixed all .import source_file paths
- Deleted stale .import files (will be regenerated by editor on open)

assets/kenney-fps/models/Textures/colormap.png.import

@@ -1,41 +0,0 @@
-[remap]
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-importer="texture"
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-uid="uid://b5hxnjwvrxuji"
-path.bptc="res://.godot/imported/colormap.png-c1bc3c3aabeec406ff4b53328583776a.bptc.ctex"
-metadata={
-"imported_formats": ["s3tc_bptc"],
-"vram_texture": true
-}
-
-[deps]
-
-source_file="res://models/Textures/colormap.png"
-dest_files=["res://.godot/imported/colormap.png-c1bc3c3aabeec406ff4b53328583776a.bptc.ctex"]
-
-[params]
-
-compress/mode=2
-compress/high_quality=true
-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=true
-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=0