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>

tools/server/build_server.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+set -eu
+
+if [ "$(uname -s)" != "FreeBSD" ]; then
+	echo "build_server.sh: 40250 server Makefile is FreeBSD-only" >&2
+	exit 2
+fi
+
+server_root=${MT40250_ROOT:-/usr/metin2}
+if [ ! -d "$server_root/src/server" ]; then
+	echo "build_server.sh: missing $server_root/src/server" >&2
+	exit 2
+fi
+if ! command -v gmake >/dev/null 2>&1; then
+	echo "build_server.sh: install gmake first" >&2
+	exit 2
+fi
+
+cd "$server_root"
+gmake -C src/server all