feat: memory panel sparkline history

modules/Memory.qml

@@ -144,6 +144,50 @@ M.BarSection {
             }
         }
 
+        // Memory history sparkline
+        Canvas {
+            id: memSparkline
+            anchors.left: parent.left
+            anchors.leftMargin: 12
+            anchors.right: parent.right
+            anchors.rightMargin: 12
+            height: 18
+
+            property var _hist: M.SystemStats.memHistory
+            property color _col: root.accentColor
+
+            on_HistChanged: if (root._showPanel)
+                requestPaint()
+            on_ColChanged: if (root._showPanel)
+                requestPaint()
+
+            Connections {
+                target: root
+                function on_ShowPanelChanged() {
+                    if (root._showPanel)
+                        memSparkline.requestPaint();
+                }
+            }
+
+            onPaint: {
+                const ctx = getContext("2d");
+                if (!ctx)
+                    return;
+                ctx.clearRect(0, 0, width, height);
+                const d = _hist;
+                if (!d.length)
+                    return;
+                const bw = width / 30;
+                ctx.fillStyle = Qt.rgba(_col.r, _col.g, _col.b, 0.15).toString();
+                ctx.fillRect(0, 0, width, height);
+                ctx.fillStyle = _col.toString();
+                for (let i = 0; i < d.length; i++) {
+                    const h = Math.max(1, height * d[i] / 100);
+                    ctx.fillRect((30 - d.length + i) * bw, height - h, Math.max(1, bw - 0.5), h);
+                }
+            }
+        }
+
         // Breakdown rows
         Item {
             width: parent.width

modules/SystemStats.qml

@@ -40,6 +40,7 @@ QtObject {
     property real memAvailGb: 0
     property real memCachedGb: 0
     property real memBuffersGb: 0
+    property var memHistory: []
 
     // ── Disk ─────────────────────────────────────────────────────────────
     property var diskMounts: []
@@ -89,6 +90,8 @@ QtObject {
                         root.memAvailGb = ev.avail_gb;
                         root.memCachedGb = ev.cached_gb;
                         root.memBuffersGb = ev.buffers_gb;
+                        const h = root.memHistory.concat([ev.percent]);
+                        root.memHistory = h.length > 30 ? h.slice(h.length - 30) : h;
                     }
                 } catch (e) {}
             }