feat(nitro): normalise hotel and uploaded bundles to WebP Lossless

Importing from a hotel wrote the downloaded .nitro to disk untouched, so
official PNG textures stayed PNG and only SWF imports ended up as WebP.
Every Studio import should produce the same format regardless of where the
bytes came from, so both clone and upload paths now run the bundle through
toWebpLosslessBundle.

The helper decodes the texture and re-encodes it with the same VP8L options
the SWF importer uses, so the artwork round-trips bit-for-bit, and lets
createNitroBundle relabel the member and repair the meta.image pointer. A
bundle that is already lossless WebP is returned untouched, making the
operation idempotent and safe to run on re-import. A colour variant that
shares a library keeps the member base name it arrived with.

A texture that cannot be decoded keeps its original format with a warning
instead of failing the import: the bundle is valid, and losing a furniture
item over a codec edge case is worse than a slightly larger texture.

src/lib/services/upload-import.test.ts

@@ -84,19 +84,16 @@ vi.mock("@/lib/services/furni-import", () => ({
 	IMPORTED_PAGE_CAPTION_SAVE: "imported_furni",
 }));
 
-const nitroBuilderMock = vi.hoisted(() => ({
-	createNitroBundle: vi.fn((json: object) =>
-		Buffer.from(`rebuilt:${JSON.stringify(json)}`, "utf-8"),
-	),
-}));
-
 vi.mock("@/lib/services/swf/nitro-builder", () => ({
 	parseNitroBundle: vi.fn(() => ({
 		json: { xdim: 1, ydim: 1 },
 		texture: Buffer.from("texture-bytes"),
 		textureFileName: "chair.png",
 	})),
-	createNitroBundle: nitroBuilderMock.createNitroBundle,
+	isLosslessWebp: vi.fn(() => false),
+	toWebpLosslessBundle: vi.fn(() =>
+		Promise.resolve(Buffer.from("webp-normalised", "utf-8")),
+	),
 }));
 
 import {
@@ -146,19 +143,13 @@ describe("uploadSingleFurni live asset mirrors", () => {
 		});
 
 		expect(result.ok).toBe(true);
-		// The bundle is re-written through the builder so `meta.image` can never
-		// disagree with the texture member, while the member keeps the name it
-		// arrived with (colour variants share a library name).
-		expect(nitroBuilderMock.createNitroBundle).toHaveBeenCalledWith(
-			{ xdim: 1, ydim: 1 },
-			Buffer.from("texture-bytes"),
-			"chair",
-		);
+		// Every upload is normalised to WebP Lossless, whatever the source
+		// bundle carried, so what lands on disk is not the raw upload.
 		await expect(
 			fs.readFile(
 				getRuntimePath(assetTargets.mirrorDirs[0].nitroDir, "chair.nitro"),
 			),
-		).resolves.toEqual(Buffer.from('rebuilt:{"xdim":1,"ydim":1}', "utf-8"));
+		).resolves.toEqual(Buffer.from("webp-normalised", "utf-8"));
 		await expect(
 			fs.readFile(
 				getRuntimePath(assetTargets.mirrorDirs[0].iconDir, "chair_icon.png"),