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>

third_party/cpython-2.7.18/RISCOS/support/!Boot

@@ -0,0 +1,22 @@
+set Python$Dir <Obey$Dir>
+set PythonApp$Path <Obey$Dir>.
+
+IconSprites <Obey$Dir>.!Sprites
+
+<Obey$Dir>.AddToPath Python$Path PythonApp:Lib
+<Obey$Dir>.AddToPath Python$Path PythonApp:Lib.plat-riscos
+<Obey$Dir>.AddToPath Python$Path PythonApp:Lib.site-packages
+set Alias$@RunType_ae5 TaskWindow |"python %%*0|" -name |"Python|" -quit -wimpslot 1248k
+| -display
+set File$Type_ae5 Python
+
+| load modules for 32 bit compatibility
+RMEnsure UtilityModule 3.10 Error This application requires RISC OS 3.10 or later
+RMEnsure UtilityModule 3.70 RMEnsure CallASWI 0.02 RMLoad System:Modules.CallASWI
+RMEnsure UtilityModule 3.70 RMEnsure CallASWI 0.02 Error This application requires CallASWI 0.02 or later
+RMEnsure FPEmulator 4.03 RMLoad System:Modules.FPEmulator
+RMEnsure FPEmulator 4.03 Error This application requires FPEmulator 4.03 or later
+RMEnsure SharedCLibrary 5.17 RMLoad System:Modules.CLib
+RMEnsure SharedCLibrary 5.34 Error This application requires SharedCLibrary 5.34 or later
+
+set Alias$Python Run <Python$Dir>.python23 %*0

third_party/cpython-2.7.18/RISCOS/support/!Run

@@ -0,0 +1,2 @@
+<Obey$Dir>.!Boot
+TaskWindow "python" -name "Python" -quit -display -wimpslot 1248k