Own legacy platform services on Linux

docs/modernization/roadmap.md

@@ -70,6 +70,12 @@ What is already real:
 - `pp_app_core`
 
 Latest slice:
+- `src/platform_legacy/legacy_platform_services.*` now exposes an ownable
+  `create_platform_services()` entrypoint alongside the legacy fallback
+  accessor.
+- `linux/src/main.cpp` now owns a local legacy `PlatformServices` instance and
+  binds it into `App` explicitly instead of binding the process-global legacy
+  accessor directly.
 - `src/app_events.cpp` no longer silently falls back to
   `pp::platform::legacy::platform_services()` when `App` has no bound platform
   services; the live app path now expects explicit platform-service ownership.

docs/modernization/tasks.md

@@ -78,6 +78,12 @@ Completed, blocked, and superseded task history moved to
   the queue is now ordered by code movement instead.
 
 Current slice:
+- `src/platform_legacy/legacy_platform_services.*` now exposes an ownable
+  `create_platform_services()` entrypoint while keeping the fallback singleton
+  for non-migrated platforms.
+- `linux/src/main.cpp` now binds an owned legacy `PlatformServices` instance
+  into `App`, making Linux the first explicit per-entrypoint owner of that
+  legacy service implementation.
 - `src/app_events.cpp` no longer hides a fallback to
   `pp::platform::legacy::platform_services()`; touched app platform dispatch
   now expects an explicitly bound platform-services pointer.

linux/src/main.cpp

@@ -55,6 +55,7 @@ void error_log(int code, const char * s)
 
 int main(int argc, char** args)
 {
+    auto platform_services = pp::platform::legacy::create_platform_services();
     GLFWwindow* wnd = nullptr;
     glfwSetErrorCallback(error_log);
     if (!glfwInit())
@@ -121,7 +122,7 @@ int main(int argc, char** args)
 
     App::I = &app;
     pp::platform::legacy::set_legacy_glfw_window(wnd);
-    app.set_platform_services(&pp::platform::legacy::platform_services());
+    app.set_platform_services(platform_services.get());
     app.initLog();
     app.create();
     app.width = 800;

src/platform_legacy/legacy_platform_services.cpp

@@ -2,6 +2,8 @@
 #include "platform_legacy/legacy_platform_services.h"
 #include "platform_legacy/legacy_platform_state.h"
 
+#include <memory>
+
 #include "legacy_ui_gl_dispatch.h"
 #include "log.h"
 #include "platform_apple/apple_platform_services.h"
@@ -552,4 +554,9 @@ PlatformServices& platform_services()
     static LegacyPlatformServices services;
     return services;
 }
+
+std::unique_ptr<PlatformServices> create_platform_services()
+{
+    return std::make_unique<LegacyPlatformServices>();
+}
 }

src/platform_legacy/legacy_platform_services.h

@@ -1,9 +1,12 @@
 #pragma once
 
+#include <memory>
+
 #include "platform_api/platform_services.h"
 
 namespace pp::platform::legacy {
 
 [[nodiscard]] PlatformServices& platform_services();
+[[nodiscard]] std::unique_ptr<PlatformServices> create_platform_services();
 
 }