refactor(Style): Add font abstraction and CSS-like styling constants

libraries/KlubhausCore/src/IDisplayDriver.h

@@ -36,6 +36,12 @@ public:
     virtual int width() = 0;
     virtual int height() = 0;
 
+    // ── Fonts ──
+    virtual void setTitleFont() = 0; // Large titles (KLUBHAUS, ALERT)
+    virtual void setBodyFont() = 0; // Normal text (status, body)
+    virtual void setLabelFont() = 0; // Small text (hints, captions)
+    virtual void setDefaultFont() = 0; // Reset to default font
+
     // ── Touch transform (for rotated panels) ──
     virtual void transformTouch(int* x, int* y) { /* default: no transform */ }
 };

libraries/KlubhausCore/src/KlubhausCore.h

@@ -7,3 +7,4 @@
 #include "IDisplayDriver.h"
 #include "NetManager.h"
 #include "ScreenState.h"
+#include "Style.h"

libraries/KlubhausCore/src/Style.h

@@ -0,0 +1,62 @@
+#pragma once
+
+#include <cstdint>
+
+struct Layout {
+    uint16_t x, y, w, h;
+
+    Layout()
+        : x(0)
+        , y(0)
+        , w(0)
+        , h(0) { }
+    Layout(uint16_t x_, uint16_t y_, uint16_t w_, uint16_t h_)
+        : x(x_)
+        , y(y_)
+        , w(w_)
+        , h(h_) { }
+
+    static Layout fullScreen(uint16_t w, uint16_t h) { return Layout(0, 0, w, h); }
+
+    static Layout header(uint16_t screenW, uint16_t headerH, uint16_t padding = 10) {
+        return Layout(0, 0, screenW, headerH);
+    }
+
+    static Layout content(
+        uint16_t screenW, uint16_t screenH, uint16_t headerH, uint16_t padding = 10) {
+        return Layout(
+            padding, headerH + padding, screenW - 2 * padding, screenH - headerH - 2 * padding);
+    }
+
+    static Layout tile(uint8_t col, uint8_t row, uint8_t cols, uint8_t rows, uint16_t contentW,
+        uint16_t contentH, uint8_t gap = 8) {
+        uint16_t tileW = (contentW - (cols - 1) * gap) / cols;
+        uint16_t tileH = (contentH - (rows - 1) * gap) / rows;
+        uint16_t x = col * (tileW + gap);
+        uint16_t y = row * (tileH + gap);
+        return Layout(x, y, tileW, tileH);
+    }
+};
+
+struct TileMetrics {
+    uint16_t tileW;
+    uint16_t tileH;
+    uint16_t gap;
+    uint8_t cols;
+    uint8_t rows;
+
+    static TileMetrics calculate(
+        uint16_t contentW, uint16_t contentH, uint8_t cols, uint8_t rows, uint8_t gap = 8) {
+        TileMetrics m;
+        m.cols = cols;
+        m.rows = rows;
+        m.gap = gap;
+        m.tileW = (contentW - (cols - 1) * gap) / cols;
+        m.tileH = (contentH - (rows - 1) * gap) / rows;
+        return m;
+    }
+
+    Layout get(uint8_t col, uint8_t row) const {
+        return Layout(col * (tileW + gap), row * (tileH + gap), tileW, tileH);
+    }
+};