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/openapi.json

@@ -1810,6 +1810,13 @@
                         "dark"
                       ]
                     },
+                    "uiFontSize": {
+                      "type": "integer",
+                      "minimum": 14,
+                      "maximum": 20,
+                      "default": 16,
+                      "description": "界面字号，与正文排版字号独立"
+                    },
                     "fontSize": {
                       "type": "integer"
                     },