Fix navbar across all pages: add nav include, fonts, active state, spacing, stats, error pages

- Add nav.php include to 5 missing pages (cost-calculator, thank-you, 403, 404, 500)
- Add ErrorDocument directives to .htaccess for custom 403/404/500 pages
- Fix bogus accuracy stats (homepage, web-scraping, location pages)
- Fix invisible CTA buttons on property and financial service pages
- Add Google Fonts (Roboto Slab + Lato) to all pages missing it (tools, blog articles, error pages)
- Add active nav link highlighting (teal underline for current page)
- Improve footer contrast to WCAG AA, equal-height cards, mobile text scaling
- Consistent navbar-to-content spacing across all pages
- Bump cache version to v1.1.3

services/property-data-extraction.php

@@ -381,7 +381,7 @@ $faqPageName = 'Property Data Extraction FAQ';
             <div class="container">
                 <h1>UK Property Data Extraction Services</h1>
                 <p class="hero-subtitle">Professional property data extraction from Rightmove, Zoopla, OnTheMarket, and other UK property portals. GDPR-compliant property market intelligence for investors, analysts, estate agents, and property developers.</p>
-                <a href="/quote" class="btn btn-white">Get a Free Consultation</a>
+                <a href="/quote" class="btn btn-primary">Get a Free Consultation</a>
             </div>
         </section>