refactor: Extract all hardcoded content to JSON files

- Move all bilingual text from templates to UI JSON (labels, buttons, modals)
- Move skills summary paragraph to CV JSON with HTML support
- Add new UI sections: navigation, viewControls, sections, footer, portfolio,
  pdfModal, shortcutsModal, infoModal, widgets
- Update Go structs to match expanded JSON structure
- Add template.HTML type for CV.SkillsSummary field
- Add JSON content validation test (70-json-content-validation.test.mjs)

Templates now contain only structural logic (CSS classes, HTML attributes)
while all user-visible text loads from JSON files for proper i18n support.

data/ui-en.json

@@ -1,19 +1,78 @@
 {
-  "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"
+  "navigation": {
+    "cvSections": "CV Sections",
+    "training": "Training",
+    "skills": "Skills",
+    "experience": "Experience",
+    "awards": "Awards",
+    "projects": "Personal / Freelance Projects",
+    "courses": "Courses",
+    "languages": "Languages",
+    "references": "References",
+    "other": "Other",
+    "quickActions": "Quick Actions",
+    "collapseAll": "Collapse All",
+    "expandAll": "Expand All",
+    "zoom": "Zoom",
+    "viewControls": "View Controls",
+    "actions": "Actions"
+  },
+  "viewControls": {
+    "length": "Length",
+    "icons": "Icons",
+    "view": "View"
+  },
+  "sections": {
+    "technicalSkills": "Technical Skills",
+    "moreSkills": "More Skills",
+    "yearsOfExperience": "years of experience",
+    "drivingLicense": "Driving License type",
+    "obtainedFrom": "obtained from the",
+    "currentBadge": "CURRENT",
+    "expiredBadge": "EXPIRED",
+    "present": "now",
+    "technologies": "Technologies:",
+    "maintainedBy": "MAINTAINED BY"
+  },
+  "footer": {
+    "viewOnGithub": "View this project on GitHub",
+    "lastUpdated": "Last updated"
+  },
+  "portfolio": {
+    "seeAllProjects": "See all projects on my",
+    "domestikaPortfolio": "Domestika portfolio"
+  },
+  "pdfModal": {
+    "title": "Download PDF",
+    "subtitle": "Choose your preferred format",
+    "preparingPdf": "Preparing PDF...",
+    "pleaseWait": "Please wait while we generate your CV",
+    "close": "Close",
+    "downloadButton": "Download PDF",
+    "shortCv": {
+      "title": "Short CV (4 pages)",
+      "pages": "4 Pages",
+      "description": "Essential info",
+      "ariaLabel": "Short CV - 4 pages, essential information"
     },
-    "viewSource": "View Project in Github",
-    "viewSourceSubtext": "Want to know how it's built?"
+    "defaultCv": {
+      "title": "Default CV (5 pages)",
+      "pages": "5 Pages",
+      "description": "Short with skills - Recommended",
+      "ariaLabel": "Default CV - 5 pages with skills (Recommended)"
+    },
+    "extendedCv": {
+      "title": "Extended CV (9 pages)",
+      "pages": "9 Pages",
+      "description": "All details",
+      "ariaLabel": "Extended CV - 9 pages, full version"
+    }
   },
   "shortcutsModal": {
     "title": "Keyboard Shortcuts",
+    "subtitle": "Learn the Shortcuts",
     "description": "Use these keyboard shortcuts to navigate and control the CV more efficiently.",
+    "close": "Close",
     "sections": {
       "zoom": {
         "title": "Zoom Control",
@@ -87,5 +146,59 @@
         }
       }
     }
+  },
+  "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 Project in Github",
+    "viewSourceSubtext": "Want to know how it's built?"
+  },
+  "widgets": {
+    "backToTop": {
+      "ariaLabel": "Back to top",
+      "tooltip": "Back to top"
+    },
+    "info": {
+      "ariaLabel": "Information",
+      "tooltip": "Information"
+    },
+    "download": {
+      "ariaLabel": "Download as PDF",
+      "tooltip": "Download as PDF"
+    },
+    "print": {
+      "ariaLabel": "Print Friendly",
+      "tooltip": "Print Friendly"
+    },
+    "shortcuts": {
+      "ariaLabel": "Keyboard shortcuts",
+      "tooltip": "Keyboard shortcuts (?)"
+    },
+    "zoomToggle": {
+      "ariaLabel": "Toggle zoom control",
+      "tooltip": "Zoom control"
+    },
+    "zoomControl": {
+      "groupLabel": "Zoom control",
+      "closeLabel": "Close zoom control",
+      "closeTitle": "Close",
+      "sliderLabel": "Adjust CV zoom level",
+      "resetLabel": "Reset zoom to 100%",
+      "resetTitle": "Reset"
+    },
+    "pdfToast": {
+      "title": "Preparing PDF",
+      "closeLabel": "Close notification"
+    },
+    "actionButtons": {
+      "downloadPdf": "Download as PDF",
+      "printFriendly": "Print Friendly"
+    }
   }
 }