chore(assets): replace app icons with the RiftLauncher rebrand

[Zaldaryon]

Replace every app icon (png, ico, icns) with the new RiftLauncher logo and remove the old VS_Launcher images that nothing references.

Changes

• resources/icon.png: new 1254x1254 compressed logo (was 500x500 old VS Launcher logo)
• resources/icon.ico: new 256x256 ICO (76 KB, was 270 KB)
• resources/icon.icns: regenerated from the new PNG at 1024/512/256/128/32/16 sizes
• resources/riftlauncher-full.png: full-resolution 1254x1254 RGBA source
• resources/riftlauncher-moddb-extended.png: 480x480 banner for ModDB (extended layout)
• resources/riftlauncher-moddb-squared.png: 480x480 banner for ModDB (squared layout)
• resources/riftlauncher.psd: Photoshop source file
• src/renderer/src/assets/icon.png: favicon for the renderer HTML
• Removed resources/VS_Launcher.png, VS_Launcher_NoBG.png, VS_Launcher_Rounded.png, VS_Launcher_Text.png (unreferenced since the rename to RiftLauncher)

Testing

All gates pass: typecheck, lint, test (1131 passing), format.

[Pixnop]

The swap itself is clean: I verified the removed VS_Launcher images are referenced nowhere on the branch (docs included), the favicon link picks up the replaced asset through vite, the new ICO carries a valid header with the same single-entry structure as the one that already worked, and the Windows packaging job accepted it. One thing to fix before merge, and it is packaging, not pixels.

electron-builder.yml has asarUnpack: resources/**, so everything in that folder ships unpacked with the app. This PR adds riftlauncher.psd (2.9 MB), riftlauncher-full.png (1.3 MB) and the two ModDB banners (134 KB) to resources, which means about 4.4 MB of design sources and marketing assets land in every installation, forever, referenced by nothing at runtime. The installer and the on-disk footprint both grow by that much. Two equally good fixes: move the design sources out of resources (a top-level design or branding folder keeps them versioned without being packaged), or add exclusions next to the existing files rules so only icon.png, icon.ico and icon.icns ship. The first is probably cleaner since nothing under resources should exist unless the app loads it.

Non-blocking note: the ICO is 256px single-entry, so Windows downscales it for the 16 and 32 pixel contexts (taskbar, title bar). The old icon had the same limitation, so nothing regresses, but a multi-size ICO generated from the same source would render crisper small, worth doing whenever the logo is next touched.

[Zaldaryon]

Moved the design sources (PSD, full-res PNG, ModDB banners) out of resources/ into a top-level branding/ directory. Only icon.png, icon.ico, and icon.icns remain in resources/ where electron-builder packages them.

The 4.4 MB of non-runtime assets no longer ship with the app.