Minimize hides only that window, Show wIRC main tray item, remember hidden main, bump to 0.1.15

- Minimizing a window hides only that window to the tray. The other windows stay
  on the desktop. Win+D still hides everything.
- Tray left click shows every hidden window at its old position, or hides them
  all if none are hidden.
- The tray menu has a new Show wIRC main item that brings back just wIRC main.
- If wIRC main was hidden when wIRC quit, it starts hidden next time and the
  servers that were connected reconnect by themselves, so their channel windows
  open without wIRC main.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/main/kotlin/data/SessionStateRepository.kt

@@ -0,0 +1,66 @@
+package data
+
+import org.json.JSONArray
+import org.json.JSONObject
+import java.io.File
+import java.nio.file.AtomicMoveNotSupportedException
+import java.nio.file.Files
+import java.nio.file.StandardCopyOption
+
+/**
+ * What wIRC looked like when it last quit: whether wIRC main was hidden to the tray, and
+ * which servers were connected. If main was hidden, the next start keeps it hidden and
+ * reconnects those servers so their channel windows open by themselves (see Main.kt).
+ */
+data class SessionState(
+    val mainHidden: Boolean = false,
+    val connectedServerIds: Set<String> = emptySet()
+)
+
+/** rootDir/session_state.json, read once at startup and written once at quit. */
+class SessionStateRepository(rootDir: File) {
+
+    private val file = File(rootDir, "session_state.json")
+    @Volatile private var saved = false
+
+    fun load(): SessionState = try {
+        if (!file.exists()) SessionState() else {
+            val obj = JSONObject(file.readText())
+            val ids = obj.optJSONArray("connectedServerIds") ?: JSONArray()
+            SessionState(
+                mainHidden = obj.optBoolean("mainHidden", false),
+                connectedServerIds = (0 until ids.length()).map { ids.getString(it) }.toSet()
+            )
+        }
+    } catch (e: Exception) {
+        SessionState()
+    }
+
+    /**
+     * Only the first call counts: quitting can reach this from more than one place (the
+     * Exit/close handlers and the JVM shutdown hook), and a later call could come after the
+     * servers were already disconnected.
+     */
+    @Synchronized
+    fun saveOnce(state: SessionState) {
+        if (saved) return
+        saved = true
+        try {
+            val obj = JSONObject().apply {
+                put("mainHidden", state.mainHidden)
+                put("connectedServerIds", JSONArray(state.connectedServerIds.toList()))
+            }
+            file.parentFile?.mkdirs()
+            // Temp file and move, same as WindowPrefsRepository, so a crash can't truncate it
+            val tmp = File(file.parentFile, "${file.name}.tmp")
+            tmp.writeText(obj.toString())
+            try {
+                Files.move(tmp.toPath(), file.toPath(), StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.ATOMIC_MOVE)
+            } catch (e: AtomicMoveNotSupportedException) {
+                Files.move(tmp.toPath(), file.toPath(), StandardCopyOption.REPLACE_EXISTING)
+            }
+        } catch (e: Exception) {
+            // Next start just opens normally
+        }
+    }
+}