feat(train): Halkyon Train's shell, Todo's copied and renamed (ADR 0030, D12)

apps/train with halkyon_train_server, _client and _flutter, as Todo's:
halkyon_base configured by trainBase(), its own register alone and a
member of the instance's where the operator names one, the app on
halkyon_app's gates with Train's frame, account sheet and About, texts
in British English and German that speak of workouts, app.halkyon.train
on Android, iOS, Linux, macOS and Windows.

Where it differs from Todo: development ports of its own (8180 to 8190),
so it runs beside Learn's server; one initial migration with the schema
Todo's migrations end at (the same tables, compared line by line), not
Todo's seventeen; and Todo's icon as a placeholder until the icon tool
of ADR 0031 draws Train's bike. The workspace, the licences, the READMEs
and AGENTS.md name it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/train/halkyon_train_flutter/windows/flutter/CMakeLists.txt

@@ -0,0 +1,109 @@
+# This file controls Flutter-level build steps. It should not be edited.
+cmake_minimum_required(VERSION 3.14)
+
+set(EPHEMERAL_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ephemeral")
+
+# Configuration provided via flutter tool.
+include(${EPHEMERAL_DIR}/generated_config.cmake)
+
+# TODO: Move the rest of this into files in ephemeral. See
+# https://github.com/flutter/flutter/issues/57146.
+set(WRAPPER_ROOT "${EPHEMERAL_DIR}/cpp_client_wrapper")
+
+# Set fallback configurations for older versions of the flutter tool.
+if (NOT DEFINED FLUTTER_TARGET_PLATFORM)
+  set(FLUTTER_TARGET_PLATFORM "windows-x64")
+endif()
+
+# === Flutter Library ===
+set(FLUTTER_LIBRARY "${EPHEMERAL_DIR}/flutter_windows.dll")
+
+# Published to parent scope for install step.
+set(FLUTTER_LIBRARY ${FLUTTER_LIBRARY} PARENT_SCOPE)
+set(FLUTTER_ICU_DATA_FILE "${EPHEMERAL_DIR}/icudtl.dat" PARENT_SCOPE)
+set(PROJECT_BUILD_DIR "${PROJECT_DIR}/build/" PARENT_SCOPE)
+set(AOT_LIBRARY "${PROJECT_DIR}/build/windows/app.so" PARENT_SCOPE)
+
+list(APPEND FLUTTER_LIBRARY_HEADERS
+  "flutter_export.h"
+  "flutter_windows.h"
+  "flutter_messenger.h"
+  "flutter_plugin_registrar.h"
+  "flutter_texture_registrar.h"
+)
+list(TRANSFORM FLUTTER_LIBRARY_HEADERS PREPEND "${EPHEMERAL_DIR}/")
+add_library(flutter INTERFACE)
+target_include_directories(flutter INTERFACE
+  "${EPHEMERAL_DIR}"
+)
+target_link_libraries(flutter INTERFACE "${FLUTTER_LIBRARY}.lib")
+add_dependencies(flutter flutter_assemble)
+
+# === Wrapper ===
+list(APPEND CPP_WRAPPER_SOURCES_CORE
+  "core_implementations.cc"
+  "standard_codec.cc"
+)
+list(TRANSFORM CPP_WRAPPER_SOURCES_CORE PREPEND "${WRAPPER_ROOT}/")
+list(APPEND CPP_WRAPPER_SOURCES_PLUGIN
+  "plugin_registrar.cc"
+)
+list(TRANSFORM CPP_WRAPPER_SOURCES_PLUGIN PREPEND "${WRAPPER_ROOT}/")
+list(APPEND CPP_WRAPPER_SOURCES_APP
+  "flutter_engine.cc"
+  "flutter_view_controller.cc"
+)
+list(TRANSFORM CPP_WRAPPER_SOURCES_APP PREPEND "${WRAPPER_ROOT}/")
+
+# Wrapper sources needed for a plugin.
+add_library(flutter_wrapper_plugin STATIC
+  ${CPP_WRAPPER_SOURCES_CORE}
+  ${CPP_WRAPPER_SOURCES_PLUGIN}
+)
+apply_standard_settings(flutter_wrapper_plugin)
+set_target_properties(flutter_wrapper_plugin PROPERTIES
+  POSITION_INDEPENDENT_CODE ON)
+set_target_properties(flutter_wrapper_plugin PROPERTIES
+  CXX_VISIBILITY_PRESET hidden)
+target_link_libraries(flutter_wrapper_plugin PUBLIC flutter)
+target_include_directories(flutter_wrapper_plugin PUBLIC
+  "${WRAPPER_ROOT}/include"
+)
+add_dependencies(flutter_wrapper_plugin flutter_assemble)
+
+# Wrapper sources needed for the runner.
+add_library(flutter_wrapper_app STATIC
+  ${CPP_WRAPPER_SOURCES_CORE}
+  ${CPP_WRAPPER_SOURCES_APP}
+)
+apply_standard_settings(flutter_wrapper_app)
+target_link_libraries(flutter_wrapper_app PUBLIC flutter)
+target_include_directories(flutter_wrapper_app PUBLIC
+  "${WRAPPER_ROOT}/include"
+)
+add_dependencies(flutter_wrapper_app flutter_assemble)
+
+# === Flutter tool backend ===
+# _phony_ is a non-existent file to force this command to run every time,
+# since currently there's no way to get a full input/output list from the
+# flutter tool.
+set(PHONY_OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/_phony_")
+set_source_files_properties("${PHONY_OUTPUT}" PROPERTIES SYMBOLIC TRUE)
+add_custom_command(
+  OUTPUT ${FLUTTER_LIBRARY} ${FLUTTER_LIBRARY_HEADERS}
+    ${CPP_WRAPPER_SOURCES_CORE} ${CPP_WRAPPER_SOURCES_PLUGIN}
+    ${CPP_WRAPPER_SOURCES_APP}
+    ${PHONY_OUTPUT}
+  COMMAND ${CMAKE_COMMAND} -E env
+    ${FLUTTER_TOOL_ENVIRONMENT}
+    "${FLUTTER_ROOT}/packages/flutter_tools/bin/tool_backend.bat"
+      ${FLUTTER_TARGET_PLATFORM} $<CONFIG>
+  VERBATIM
+)
+add_custom_target(flutter_assemble DEPENDS
+  "${FLUTTER_LIBRARY}"
+  ${FLUTTER_LIBRARY_HEADERS}
+  ${CPP_WRAPPER_SOURCES_CORE}
+  ${CPP_WRAPPER_SOURCES_PLUGIN}
+  ${CPP_WRAPPER_SOURCES_APP}
+)

apps/train/halkyon_train_flutter/windows/flutter/generated_plugin_registrant.cc

@@ -0,0 +1,29 @@
+//
+//  Generated file. Do not edit.
+//
+
+// clang-format off
+
+#include "generated_plugin_registrant.h"
+
+#include <connectivity_plus/connectivity_plus_windows_plugin.h>
+#include <desktop_webview_window/desktop_webview_window_plugin.h>
+#include <file_selector_windows/file_selector_windows.h>
+#include <flutter_secure_storage_windows/flutter_secure_storage_windows_plugin.h>
+#include <url_launcher_windows/url_launcher_windows.h>
+#include <window_to_front/window_to_front_plugin.h>
+
+void RegisterPlugins(flutter::PluginRegistry* registry) {
+  ConnectivityPlusWindowsPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("ConnectivityPlusWindowsPlugin"));
+  DesktopWebviewWindowPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("DesktopWebviewWindowPlugin"));
+  FileSelectorWindowsRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("FileSelectorWindows"));
+  FlutterSecureStorageWindowsPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("FlutterSecureStorageWindowsPlugin"));
+  UrlLauncherWindowsRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("UrlLauncherWindows"));
+  WindowToFrontPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("WindowToFrontPlugin"));
+}

apps/train/halkyon_train_flutter/windows/flutter/generated_plugin_registrant.h

@@ -0,0 +1,15 @@
+//
+//  Generated file. Do not edit.
+//
+
+// clang-format off
+
+#ifndef GENERATED_PLUGIN_REGISTRANT_
+#define GENERATED_PLUGIN_REGISTRANT_
+
+#include <flutter/plugin_registry.h>
+
+// Registers Flutter plugins.
+void RegisterPlugins(flutter::PluginRegistry* registry);
+
+#endif  // GENERATED_PLUGIN_REGISTRANT_

apps/train/halkyon_train_flutter/windows/flutter/generated_plugins.cmake

@@ -0,0 +1,30 @@
+#
+# Generated file, do not edit.
+#
+
+list(APPEND FLUTTER_PLUGIN_LIST
+  connectivity_plus
+  desktop_webview_window
+  file_selector_windows
+  flutter_secure_storage_windows
+  url_launcher_windows
+  window_to_front
+)
+
+list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
+)
+
+set(PLUGIN_BUNDLED_LIBRARIES)
+
+foreach(plugin ${FLUTTER_PLUGIN_LIST})
+  add_subdirectory(flutter/ephemeral/.plugin_symlinks/${plugin}/windows plugins/${plugin})
+  target_link_libraries(${BINARY_NAME} PRIVATE ${plugin}_plugin)
+  list(APPEND PLUGIN_BUNDLED_LIBRARIES $<TARGET_FILE:${plugin}_plugin>)
+  list(APPEND PLUGIN_BUNDLED_LIBRARIES ${${plugin}_bundled_libraries})
+endforeach(plugin)
+
+foreach(ffi_plugin ${FLUTTER_FFI_PLUGIN_LIST})
+  add_subdirectory(flutter/ephemeral/.plugin_symlinks/${ffi_plugin}/windows plugins/${ffi_plugin})
+  list(APPEND PLUGIN_BUNDLED_LIBRARIES ${${ffi_plugin}_bundled_libraries})
+endforeach(ffi_plugin)