layout: restructure into src/ tests/ android/ scripts/ tools/

- extension/src/{port,platform,codepage} -> src/; native_render -> src/host
  (+ dxt, shaders/); libgr2 -> src/gr2; extension/third_party -> third_party
- extension/tests -> tests/port, libgr2/tests -> tests/gr2
- android-native -> android (build.sh, push-client.sh moved in)
- script -> scripts; tools/40250 -> tools/server; oracle -> tools/granny-oracle;
  perf tools -> tools/perf
- all build trees under build/ (native, release, android, port-gate)
- xrender:: CMake aliases -> mt::; port-map ledger impl paths rewritten

No code changes. ctest 15/15, port_gate macos+android PASS, port_map check 0 errors.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/THIRD-PARTY.md

@@ -2,7 +2,7 @@
 
 The native client links four vendored libraries, all built from source by our own
 CMake build (the Android NDK and iOS SDK sysroots have none of them). They live under
-`extension/third_party/` and are wired by `extension/third_party/CMakeLists.txt`.
+`third_party/` and are wired by `third_party/CMakeLists.txt`.
 libsodium and zstd (the m2dev-era net/pack layers) were removed on 2026-09-29 together
 with those layers.
 
@@ -17,7 +17,7 @@ with those layers.
 
 ## miniLZO — vendored source (not a submodule)
 
-* **Files:** `extension/third_party/minilzo/{minilzo.c,minilzo.h,lzoconf.h,lzodefs.h}`
+* **Files:** `third_party/minilzo/{minilzo.c,minilzo.h,lzoconf.h,lzodefs.h}`
   copied verbatim from **lzo-2.10** (`minilzo.c` sha1 `019debb3…`), plus
   `README.LZO`, `COPYING`, `AUTHORS` as required by the LZO license.
 * Upstream LZO has no git repo (oberhumer.com tarball only), and miniLZO is a
@@ -27,14 +27,14 @@ with those layers.
   miniLZO's API (`lzo_init`, `lzo1x_decompress_safe`, `LZO_E_OK`, `lzo_uint`) is a
   strict subset of full LZO and covers everything the CLZO path uses.
 * **License:** **GPLv2**. Acceptable for this internal, non-published,
-  non-commercial project on the same footing as `libgr2/src/oodle1.c` — but LZO
+  non-commercial project on the same footing as `src/gr2/src/oodle1.c` — but LZO
   must be removed, replaced, or commercially licensed before any public release
   or commercial use. (item_proto/mob_proto are the only LZO consumers; a
   clean-room LZO1X decompressor is the eventual fix.)
 
 ## Crypto++ — vendored source (not a submodule)
 
-* **Files:** `extension/third_party/cryptopp/` (~6.6 MB), copied from the 40250
+* **Files:** `third_party/cryptopp/` (~6.6 MB), copied from the 40250
   client tree (`ClientVS22/extern/include/cryptopp`), `CRYPTOPP_VERSION 840` =
   **8.4.0**. The 40250 server links this exact version
   (`Server/.../extern/cryptopp_8_4_0.tar.gz`), so the version is pinned by
@@ -56,12 +56,12 @@ with those layers.
   `-fno-strict-aliasing`.
 * **License:** **public domain** — the compilation carries Wei Dai's copyright,
   but every individual file is placed in the public domain by its authors
-  (`extension/third_party/cryptopp/License.txt`). Ship-safe; unlike miniLZO it
+  (`third_party/cryptopp/License.txt`). Ship-safe; unlike miniLZO it
   imposes no obligation before a public or commercial release.
 
 ## CPython 2.7.18 — vendored source (not a submodule)
 
-* **Files:** `extension/third_party/cpython-2.7.18/` (~25 MB), the official
+* **Files:** `third_party/cpython-2.7.18/` (~25 MB), the official
   `Python-2.7.18.tgz` (sha256 `b62c0e7937551d0cc02b8fd5cb0f544f9405bafc9a54d3808ed4594812edef43`)
   trimmed of what an embedded interpreter never builds or ships: `Doc Demo Tools
   Mac PCbuild`, `Modules/{_ctypes,expat,zlib,_sqlite}`, the stdlib test trees and
@@ -110,7 +110,7 @@ with those layers.
 
 ## FreeType 2.13.3 — vendored source, trimmed (not a submodule)
 
-* **Files:** `extension/third_party/freetype-2.13.3/` (~5 MB): the official
+* **Files:** `third_party/freetype-2.13.3/` (~5 MB): the official
   `freetype-2.13.3.tar.xz` (source URL and sha256 in the directory's
   `CMakeLists.txt` header) cut down to `include/`, `src/{base,sfnt,truetype,smooth,raster,psnames,gzip}`,
   `LICENSE.TXT` and `docs/FTL.TXT`.