refactor: separate UI translations from CV data

- Created separate ui-en.json and ui-es.json files for UI strings
- Removed 'ui' section from cv-en.json and cv-es.json
- Added LoadUI() function to load UI translations separately
- Updated handlers to load UI data independently from CV data
- Updated template to use .UI instead of .CV.UI

This separation follows proper concerns:
- CV JSON files contain only professional CV content
- UI JSON files contain only application interface strings
- Each can be updated independently without affecting the other

data/ui-en.json

@@ -0,0 +1,13 @@
+{
+  "infoModal": {
+    "title": "About this CV",
+    "description": "This interactive CV was built by myself with <strong>Go + HTMX</strong>, showcasing modern hypermedia architecture without heavy JavaScript frameworks.",
+    "techStack": {
+      "goHono": "Go + Hono",
+      "htmx": "HTMX",
+      "html5": "Semantic HTML5",
+      "css3": "Pure CSS3"
+    },
+    "viewSource": "View Source Code"
+  }
+}