fix(texture): correct Xenos de-tile + endian + cubemaps + PNG export

Reworks the XPR2 texture path after RE against the retail disc (viewer
previews were scrambled/failed).

- de-tile: replace the naive Morton-over-32×32 approximation with the
  faithful Xenos Tiled2D bank/pipe/macro-tile address formula (ported
  from xenia texture_address.h). Verified correct: the Acheron backdrop
  decodes to a sharp planet with its spiral storm.
- endian: undo the X360 word byte-swap per the fetch-constant endianness
  field (k8in16/k8in32/k16in32) — without it BCn/ARGB data is noise.
- cubemaps: parse TXCM resources (skybox/backdrops), decoding face 0,
  instead of erroring "No TX2D found".
- A8R8G8B8: correct channel order after the k8in32 swap ([A,R,G,B]→RGBA)
  — the Acheron backdrop is now correctly green, not red.
- XPR files are texture PACKS; add XPR_RES_INDEX to select a resource.
- CLI `texture export` now writes real PNGs (texpresso BCn decode +
  image), replacing the stub. Adds texpresso + image deps.
- tests/texture_disc.rs: integration test running the pipeline over real
  disc .xpr files (28/28 parse). RE debug knobs: XPR_NO_DETILE /
  XPR_NO_ENDIAN / XPR_FORCE_ENDIAN.

KNOWN ISSUE: mipmapped DXT1 textures still decode to noise — mip 0 is
not at base_address in the multi-resource packs (localized to a mip
storage-offset quirk; uncompressed + de-tile + endian are all verified).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Cargo.lock

@@ -4345,8 +4345,10 @@ dependencies = [
  "anyhow",
  "clap",
  "colored",
+ "image",
  "indicatif",
  "sylpheed-formats",
+ "texpresso",
  "tokio",
  "tracing",
  "tracing-subscriber",
@@ -4437,6 +4439,15 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "texpresso"
+version = "2.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8550677e2259d675a7841cb1403db35f330cc9e58674c8c5caa12dd12c51dc71"
+dependencies = [
+ "libm",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.69"