chore(testing): add DevelopTest sandbox for manual API experiments

Personal scratch test under src/test/java/com/demcha/testing/visual/.
Renders to target/visual-tests/develop/Develop.pdf. Edit scratch()
freely to try new helpers and layouts without disturbing other tests.

ASCII-only until v1.6.2 R1 glyph sanitizer lands — Helvetica
WinAnsiEncoding crashes on arrows / dots / emoji until then.

Author: DemchaAV

src/test/java/com/demcha/testing/visual/DevelopTest.java

@@ -0,0 +1,81 @@
+package com.demcha.testing.visual;
+
+import com.demcha.compose.GraphCompose;
+import com.demcha.compose.document.api.DocumentSession;
+import com.demcha.compose.document.style.DocumentInsets;
+import com.demcha.compose.document.theme.BusinessTheme;
+import com.demcha.testing.VisualTestOutputs;
+import org.junit.jupiter.api.Test;
+
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Personal sandbox / scratch test for manual GraphCompose API experimentation.
+ *
+ * <p>Renders a minimal document to
+ * {@code target/visual-tests/develop/Develop.pdf}. Edit {@link #scratch()}
+ * freely to try new helpers, layouts, theme tweaks, or upcoming v1.7+ APIs.
+ * Open the rendered PDF in any viewer to see the result.</p>
+ *
+ * <p><b>Unicode safety</b>: until v1.6.2 ships (R1 glyph sanitizer), keep
+ * to ASCII in the body. The current PDF font path crashes on any glyph
+ * that Helvetica's WinAnsiEncoding cannot encode (arrows, dots, emoji).
+ * After v1.6.2: replace ASCII placeholders with actual symbols freely.</p>
+ *
+ * <p>Run from repo root:
+ * <pre>{@code
+ * mvnw test -Dtest=DevelopTest -pl .
+ * }</pre>
+ *
+ * <p>This file is intentionally committed as a working sandbox; rewrite the
+ * body of {@link #scratch()} as needed — the only stable contract is that
+ * the test produces a {@code Develop.pdf} starting with the {@code %PDF-}
+ * header.</p>
+ *
+ * @author Artem Demchyshyn
+ */
+class DevelopTest {
+
+    private static final BusinessTheme THEME = BusinessTheme.modern();
+
+    @Test
+    void scratch() throws Exception {
+        Path output = VisualTestOutputs.preparePdf("Develop", "develop");
+
+        try (DocumentSession document = GraphCompose.document()
+                .pageSize(595, 842)
+                .pageBackground(THEME.pageBackground())
+                .margin(DocumentInsets.of(28))
+                .create()) {
+
+            document.pageFlow(page -> page
+                    .addSection("Hero", section -> section
+                            .softPanel(THEME.palette().surfaceMuted(), 10, 14)
+                            .accentLeft(THEME.palette().accent(), 4)
+                            .addParagraph(p -> p.text("DevelopTest")
+                                    .textStyle(THEME.text().h1()))
+                            .addParagraph(p -> p.text(
+                                            "Scratch space for manual API experiments. "
+                                                    + "Render -> open -> think -> iterate.")
+                                    .textStyle(THEME.text().body())))
+
+                    .addSection("Body", section -> section
+                            .addParagraph(p -> p.text(
+                                            "Replace this body with anything you want to try. "
+                                                    + "After v1.6.2: emoji, dots, unicode are safe. "
+                                                    + "After v1.7+: .h1(), .addFieldRow(), .twoColumn(), "
+                                                    + ".addHeadingBar(), .ratingDots(), .pageTopBand().")
+                                    .textStyle(THEME.text().body()))));
+
+            Files.write(output, document.toPdfBytes());
+        }
+
+        byte[] bytes = Files.readAllBytes(output);
+        assertThat(bytes).isNotEmpty();
+        assertThat(new String(bytes, 0, 5, StandardCharsets.US_ASCII)).isEqualTo("%PDF-");
+    }
+}