feat: enhance CV with project title links, experience durations, certifications, and improved navigation

## Project Title Links
- Add projectName and projectDesc fields to Project struct
- Split project titles to make only project name clickable
- Update template logic for conditional title rendering
- Apply changes to both English and Spanish versions

## Experience Duration Display
- Restore duration calculation display in experience section
- Move duration from date line to after company name
- Style duration in light gray (#999) for subtle appearance
- Calculate durations dynamically (e.g., "4 years 10 months")

## Certifications Section Enhancement
- Add Codecademy Certifications (2022-2024) with AI Transformers and React courses
- Add LinkedIn Learning Certifications (2019-2020) with 5 professional courses
- Implement colored icon system with brand colors (purple, cyan, green, etc.)
- Use responsibilities format matching Third Party Contributions layout
- Reorder courses chronologically (most recent first)

## localStorage Improvements
- Save CV length preference (short/long)
- Save logos visibility preference (show/hide)
- Save theme preference (default/clean)
- Restore all preferences on page load

## Navigation UX Enhancements
- Fix scroll positioning to show sections below action bar
- Add keepHeaderVisible flag to maintain header visibility after navigation
- Ensure smooth scrolling with proper offset calculations
- Reset flag on scroll up to restore normal hide/show behavior

## Files Modified
- internal/models/cv.go: Add ProjectName, ProjectDesc fields
- templates/cv-content.html: Update project and experience rendering
- static/css/main.css: Add duration-text styling
- templates/index.html: Enhance scroll behavior and localStorage
- data/cv-*.json: Add certifications, split project titles, reorder courses
- static/images/courses/: Add codecademy.png, linkedin.png

static/css/main.css

@@ -779,6 +779,11 @@ iconify-icon {
     margin-top: 0.5rem;
 }
 
+.duration-text {
+    color: #999;
+    font-weight: normal;
+}
+
 .responsibilities {
     list-style: none;
     margin-top: 1rem;