feat(ui): improve readability and fix workspace regressions

Separate interface typography from document text and enlarge controls across the workspace and public reader. Keep tree menus within the viewport and make constrained dialogs scrollable.

Preserve nested image references, escape moved link paths, synchronize note creation and daily-note opening, and hydrate shared headings. Add regression coverage for settings and workspace behavior.

internal/api/themes_test.go

@@ -43,7 +43,7 @@ func TestThemeAndShareAppearanceBoundaries(t *testing.T) {
 		t.Fatal("未读取到主题 CSS")
 	}
 	f.write("笔记.md", "正文")
-	f.do(f.admin, "PATCH", "/api/v1/settings", `{"theme":"paper","colorMode":"dark","fontSize":18,"privateSetting":"不公开","cssSnippets":[{"id":"a","name":"启用","css":"body { color: red }","enabled":true},{"id":"b","name":"停用","css":"不公开片段","enabled":false}]}`, nil)
+	f.do(f.admin, "PATCH", "/api/v1/settings", `{"theme":"paper","colorMode":"dark","fontSize":18,"uiFontSize":20,"privateSetting":"不公开","cssSnippets":[{"id":"a","name":"启用","css":"body { color: red }","enabled":true},{"id":"b","name":"停用","css":"不公开片段","enabled":false}]}`, nil)
 	sh := decode[shareView](t, f.do(f.admin, "POST", "/api/v1/shares", `{"path":"笔记.md","password":"访问密码"}`, nil))
 	base := "/api/v1/public/shares/" + sh.Token
 	if code := f.status(guest, "GET", base+"/appearance", "", nil); code != 401 {
@@ -59,7 +59,7 @@ func TestThemeAndShareAppearanceBoundaries(t *testing.T) {
 	if err := json.Unmarshal(raw, &appearance); err != nil {
 		t.Fatal(err)
 	}
-	if res.StatusCode != 200 || appearance["colorMode"] != "dark" || !strings.Contains(appearance["themeCSS"].(string), "#faf6ed") {
+	if res.StatusCode != 200 || appearance["colorMode"] != "dark" || appearance["uiFontSize"] != float64(20) || appearance["fontSize"] != float64(18) || !strings.Contains(appearance["themeCSS"].(string), "#faf6ed") {
 		t.Fatalf("分享外观错误：%s", raw)
 	}
 	if strings.Contains(string(raw), "不公开") || len(appearance["cssSnippets"].([]any)) != 1 {