test(ttf): Añadir tests con AdwaitaSans real

- Test carga fuente del sistema
- Verificar parsing de contornos para 'A'
- Verificar rasterización produce bitmap con datos
- Test múltiples caracteres (AaBb0123)
- Tests skip gracefully si fuente no disponible

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/render/ttf.zig

@@ -1062,3 +1062,83 @@ test "readU32Big" {
     const data = [_]u8{ 0x12, 0x34, 0x56, 0x78 };
     try std.testing.expectEqual(@as(u32, 0x12345678), readU32Big(&data, 0));
 }
+
+test "TTF load and rasterize AdwaitaSans" {
+    const allocator = std.testing.allocator;
+
+    // Try to load AdwaitaSans from system
+    var font = TtfFont.loadFromFile(allocator, "/usr/share/fonts/adwaita-sans-fonts/AdwaitaSans-Regular.ttf") catch {
+        // Font not available on this system, skip test
+        return;
+    };
+    defer font.deinit();
+
+    // Verify font was parsed correctly
+    try std.testing.expect(font.num_glyphs > 0);
+    try std.testing.expect(font.metrics.units_per_em > 0);
+
+    // Get glyph index for 'A'
+    const glyph_index = font.getGlyphIndex('A');
+    try std.testing.expect(glyph_index > 0);
+
+    // Get glyph outline
+    if (font.getGlyphOutline(glyph_index)) |outline| {
+        var outline_mut = outline;
+        defer outline_mut.deinit();
+
+        // 'A' should have contours (typically 2: outer and inner)
+        try std.testing.expect(outline.contours.len > 0);
+
+        // Rasterize
+        font.setSize(24);
+        if (rasterizeGlyph(allocator, outline, font.scale, 2)) |bitmap| {
+            var bitmap_mut = bitmap;
+            defer bitmap_mut.deinit();
+
+            // Should produce a bitmap with non-zero dimensions
+            try std.testing.expect(bitmap.width > 0);
+            try std.testing.expect(bitmap.height > 0);
+
+            // Should have some non-zero alpha values (actual glyph data)
+            var has_content = false;
+            for (bitmap.data) |alpha| {
+                if (alpha > 0) {
+                    has_content = true;
+                    break;
+                }
+            }
+            try std.testing.expect(has_content);
+        }
+    }
+}
+
+test "TTF rasterize multiple characters" {
+    const allocator = std.testing.allocator;
+
+    var font = TtfFont.loadFromFile(allocator, "/usr/share/fonts/adwaita-sans-fonts/AdwaitaSans-Regular.ttf") catch {
+        return; // Skip if font not available
+    };
+    defer font.deinit();
+
+    font.setSize(16);
+
+    // Test several characters
+    const test_chars = "AaBb0123";
+    for (test_chars) |c| {
+        const glyph_index = font.getGlyphIndex(c);
+        if (glyph_index == 0) continue;
+
+        if (font.getGlyphOutline(glyph_index)) |outline| {
+            var outline_mut = outline;
+            defer outline_mut.deinit();
+
+            if (rasterizeGlyph(allocator, outline, font.scale, 2)) |bitmap| {
+                var bitmap_mut = bitmap;
+                defer bitmap_mut.deinit();
+
+                try std.testing.expect(bitmap.width > 0);
+                try std.testing.expect(bitmap.height > 0);
+            }
+        }
+    }
+}