feat(ui): implement FontsUtil for consistent font sizing across Swing components

Author: lakernote

.codex/skills/swing-ui-test-headless-guard/SKILL.md

@@ -0,0 +1,26 @@
+---
+name: swing-ui-test-headless-guard
+description: Use when adding or updating EasyPostman Swing/TestNG UI tests that may run in headless CI. Extract and reuse the shared skip logic from AbstractSwingUiTest instead of duplicating DISPLAY/headless checks in each test.
+---
+
+# Swing UI Test Headless Guard
+
+Use this skill for Swing UI tests under `easy-postman-app/src/test/java`.
+
+## Default pattern
+
+1. Put shared no-display skip logic in:
+   `easy-postman-app/src/test/java/com/laker/postman/test/AbstractSwingUiTest.java`
+2. Make Swing/UI tests extend that base class.
+3. Use `@BeforeClass` + `SkipException` to skip tests when:
+   - `GraphicsEnvironment.isHeadless()` is `true`
+   - or Linux has neither `DISPLAY` nor `WAYLAND_DISPLAY`
+
+## Guardrails
+
+- Keep the base class narrow. Only put environment-skip behavior there unless multiple UI tests clearly need more.
+- Do not add this base class to non-UI tests.
+- Prefer `SkipException` over brittle per-test conditionals.
+- After changes, verify with:
+  - `mvn -q -pl easy-postman-app -am -DskipTests compile`
+  - `mvn -q -pl easy-postman-app -am -Dtest=<TestClass> -Dsurefire.failIfNoSpecifiedTests=false -Djava.awt.headless=true test`

AGENTS.md

@@ -4,6 +4,7 @@
 
 - swing-flatlaf-miglayout-principles: Use when modifying EasyPostman Swing forms that use FlatLaf and MigLayout, especially when layout refactors introduce clipped focus rings, dense spacing, border conflicts, or inconsistent form structure. (file: /Users/lonli2/IdeaProjects-laker/easy-postman-github/.codex/skills/swing-flatlaf-miglayout-principles/SKILL.md)
 - fontsutil-font-usage: Use when modifying EasyPostman Swing UI fonts, especially when dialogs, labels, tables, tabs, or renderers look too large or too small, or when a change must follow the user's configured UI font size. Prefer FontsUtil.getDefaultFontWithOffset(...). (file: /Users/lonli2/IdeaProjects-laker/easy-postman-github/.codex/skills/fontsutil-font-usage/SKILL.md)
+- swing-ui-test-headless-guard: Use when adding or updating EasyPostman Swing/TestNG UI tests that may run in headless CI. Reuse `AbstractSwingUiTest` instead of duplicating headless or no-display skip logic. (file: /Users/lonli2/IdeaProjects-laker/easy-postman-github/.codex/skills/swing-ui-test-headless-guard/SKILL.md)
 
 ### How to use skills
 

easy-postman-app/src/test/java/com/laker/postman/panel/collections/right/request/RequestPreparationFeedbackHelperTest.java

@@ -1,14 +1,15 @@
 package com.laker.postman.panel.collections.right.request;
 
 import com.formdev.flatlaf.FlatClientProperties;
+import com.laker.postman.test.AbstractSwingUiTest;
 import org.testng.annotations.Test;
 
 import javax.swing.*;
 
 import static org.testng.Assert.assertEquals;
 import static org.testng.Assert.assertNull;
 
-public class RequestPreparationFeedbackHelperTest {
+public class RequestPreparationFeedbackHelperTest extends AbstractSwingUiTest {
 
     @Test(description = "清理 URL 校验反馈时只应清除 outline，不应改动 tooltip")
     public void testClearUrlValidationFeedback_ShouldOnlyClearOutline() {

easy-postman-app/src/test/java/com/laker/postman/test/AbstractSwingUiTest.java

@@ -0,0 +1,36 @@
+package com.laker.postman.test;
+
+import org.testng.SkipException;
+import org.testng.annotations.BeforeClass;
+
+import java.awt.*;
+
+public abstract class AbstractSwingUiTest {
+
+    @BeforeClass
+    public void skipWhenNoDisplayEnvironment() {
+        if (shouldSkipForHeadlessEnvironment()) {
+            throw new SkipException("Skipping Swing UI test in headless/no-display environment");
+        }
+    }
+
+    protected boolean shouldSkipForHeadlessEnvironment() {
+        if (GraphicsEnvironment.isHeadless()) {
+            return true;
+        }
+
+        String osName = System.getProperty("os.name", "").toLowerCase();
+        boolean linuxLike = osName.contains("linux");
+        if (!linuxLike) {
+            return false;
+        }
+
+        String display = System.getenv("DISPLAY");
+        String waylandDisplay = System.getenv("WAYLAND_DISPLAY");
+        return isBlank(display) && isBlank(waylandDisplay);
+    }
+
+    private boolean isBlank(String value) {
+        return value == null || value.trim().isEmpty();
+    }
+}