feat(platform): add NX capability detection module

Co-authored-by: Cursor <cursoragent@cursor.com>

src/core/Platform.lua

@@ -0,0 +1,54 @@
+-- Platform capability detection for NX / mobile / desktop.
+
+local Platform = {}
+
+local cached
+
+local function compute()
+  local osName = (love and love.system and love.system.getOS and love.system.getOS())
+    or "Unknown"
+  local nx = osName == "NX"
+  local mobile = osName == "Android" or osName == "iOS"
+  local nativePicker = love and love.system
+    and type(love.system.pickFile) == "function"
+  return {
+    os = osName,
+    nx = nx,
+    mobile = mobile,
+    console = nx,
+    hasNativePicker = nativePicker,
+    canSpawnProcess = osName == "OS X" or osName == "Windows" or osName == "Linux",
+    romImportMode = nx and "save-directory"
+      or (nativePicker and "native-picker")
+      or "desktop",
+    networkValidated = not nx,
+  }
+end
+
+function Platform.detect()
+  if not cached then cached = compute() end
+  return cached
+end
+
+function Platform.isNX()
+  return Platform.detect().nx
+end
+
+function Platform.romImportMode()
+  return Platform.detect().romImportMode
+end
+
+function Platform.canSpawnProcess()
+  return Platform.detect().canSpawnProcess
+end
+
+function Platform.networkValidated()
+  return Platform.detect().networkValidated
+end
+
+-- Tests may swap love.system between cases.
+function Platform._resetForTests()
+  cached = nil
+end
+
+return Platform