feat: add social links to footer and optional company logo toggle

**Social Links in Footer (Page 2):**
- Replace address/phone with LinkedIn, GitHub, and Behance links
- Maintain email@ link
- All links are clickable and open in new tabs
- Footer displays social media profiles prominently

**Company Logo Toggle Feature:**
- Add "Show logos" toggle switch in top action bar
- Toggle displays company logos (48x48px) to the left of each experience item
- LinkedIn-style layout when logos are shown
- Logos hidden by default, optional display via toggle
- Graceful fallback: missing logos don't break layout (onerror handler)
- Logos directory created at static/images/logos/ with README

**Technical Implementation:**
- New CSS file: logo-toggle.css for toggle switch and logo layout
- JavaScript: toggleLogos() function for show/hide functionality
- Template updates: experience items now support flex layout with logos
- Action bar grid updated to accommodate 4 columns
- Logo display uses CSS class `.show-logos` on `.cv-paper`
- Print CSS: logos hidden in PDF exports by default

**User Experience:**
- Clean toggle switch UI with smooth animations
- Mobile responsive design
- Accessibility: proper ARIA labels for toggle
- Optional feature that doesn't clutter default view
- Professional LinkedIn-style appearance when enabled

Logos can be added to static/images/logos/ directory using filenames
from the companyLogo field in CV JSON data.

static/images/logos/README.md

@@ -0,0 +1,25 @@
+# Company Logos
+
+Place company logos here with the filenames matching the `companyLogo` field in the CV JSON data.
+
+## Expected Format:
+- **Size**: 48x48px minimum (will be displayed at 48x48px)
+- **Format**: PNG or SVG preferred
+- **Background**: Transparent or white
+- **Naming**: Should match exactly the filename in `cv-en.json` / `cv-es.json`
+
+## Current logos needed:
+- olympic-broadcasting.png
+- aena.png
+- sap.png
+- gigya.png
+- everis.png
+- megabanner.png
+- ebantic.png
+- indra.png
+- emailing-network.png
+- penta-msi.png
+- homeria.png
+- insa.png
+
+Note: Logos are optional. If a logo file doesn't exist, it will be hidden gracefully.