StemRoller: desktop stem separator, Android stems player, and server daemons

- stemroller/: PySide6/QML desktop app and player for separating music into stems
- android/: Plex music player that plays per-stem mixes, with Android Auto support,
  a graphic + parametric (Equalizer APO-style) EQ, and offline downloads
- server/: stemserve (serves stems to the app) and stemd (separates the library on
  the server's GPU, with "Stem Now" priority requests)

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

stemroller/qml/StemRoller/Theme.qml

@@ -0,0 +1,65 @@
+pragma Singleton
+import QtQuick
+
+// Design tokens: Material structure (8dp grid, type ramp, motion), Aero surface.
+QtObject {
+    // dark gray tokens
+    readonly property color bg: "#1D1E21"
+    readonly property color surface1: "#26272B"
+    readonly property color surface2: "#2F3034"
+    readonly property color glassTint: Qt.rgba(36 / 255, 37 / 255, 41 / 255, 0.70)
+    readonly property color primary: "#3BA8FF"
+    readonly property color accentGlow: "#5FE3FF"
+    readonly property color success: "#4CD07D"
+    readonly property color error: "#FF5C6C"
+    readonly property color warning: "#FFB547"
+    readonly property color textHi: "#ECEDEF"
+    readonly property color textLo: "#9B9DA3"
+    readonly property color outline: Qt.rgba(1, 1, 1, 0.08)
+    readonly property color hairline: Qt.rgba(1, 1, 1, 0.06)
+
+    // 8dp grid
+    readonly property int u: 8
+
+    // type ramp 12 / 14 / 16 / 20 / 28
+    property string fontFamily: "Inter"
+    readonly property int fs12: 12
+    readonly property int fs14: 14
+    readonly property int fs16: 16
+    readonly property int fs20: 20
+    readonly property int fs28: 28
+
+    // motion: Material standard easing, nothing over 300 ms
+    readonly property int fast: 100
+    readonly property int med: 200
+    readonly property int slow: 300
+    readonly property var ease: [0.2, 0, 0, 1, 1, 1]
+
+    // elevation: blur sigma, alpha, y offset per level
+    readonly property var shadowSigma: [0, 2, 4, 8]
+    readonly property var shadowAlpha: [0, 0.35, 0.45, 0.55]
+    readonly property var shadowDy: [0, 1, 2, 4]
+
+    readonly property var stemColors: ({
+        "vocals": "#FF7AB6", "drums": "#FFB547", "bass": "#7C8CFF", "other": "#4CD07D",
+        "guitar": "#FF8A5C", "piano": "#B48CFF", "instrumental": "#3DD6C6"
+    })
+    readonly property var stemIcons: ({
+        "vocals": "music", "drums": "equalizer", "bass": "speed", "other": "layers",
+        "guitar": "music", "piano": "music", "instrumental": "layers"
+    })
+
+    function alpha(c, a) { return Qt.rgba(c.r, c.g, c.b, a) }
+    function hex(c) { return c.toString().substring(1, 7).toUpperCase() }
+    function icon(name, color) { return "image://icon/" + name + "/" + hex(color) }
+    function stemColor(name) { return stemColors[name] || "#9B9DA3" }
+
+    function time(sec, tenths) {
+        if (!isFinite(sec) || sec < 0) sec = 0
+        var m = Math.floor(sec / 60)
+        var s = sec - m * 60
+        var ss = tenths ? s.toFixed(1) : Math.floor(s).toString()
+        if ((tenths && s < 10) || (!tenths && s < 10)) ss = "0" + ss
+        return m + ":" + ss
+    }
+}