feat: Transform HookLab to OBC Maçonnerie showcase site

Complete transformation of the Next.js project into a professional
showcase site for OBC Maçonnerie (Benoît Colin, maçon in Nord 59).

Key changes:
- Remove all HookLab/Sanity/Supabase/Stripe/admin/training infrastructure
- Full OBC Maçonnerie identity: logo, colors, contact info, SIREN
- Schema.org LocalBusiness structured data for Benoît Colin
- SEO metadata for all pages targeting Nord 59 keywords

New pages created (23 total):
- Home page with 10 sections (hero, services, pillars, partners,
  zone, realisations, testimonials, FAQ, contact form, footer)
- Service pages: construction-maison, renovation, assainissement,
  creation-acces, demolition, services
- Secondary pages: realisations, partenaires, contact
- Blog: listing + 6 SEO articles with static content
- 8 local SEO pages: Orchies, Douai, Valenciennes, Mouchin,
  Flines-lès-Raches, Saint-Amand-les-Eaux
- Legal pages: mentions-legales, cgv, confidentialite (OBC adapted)

Components:
- Navbar with OBC branding + mobile menu
- Footer with dark navy theme, services + navigation links
- ContactForm client component (devis request)
- LocalSEOPage reusable component for local SEO pages
- CookieBanner updated with OBC cookie key

Config:
- layout.tsx: OBC metadata, Schema.org, no Sanity CDN
- globals.css: stone color variables added
- next.config.ts: removed Sanity CDN remotePatterns
- sitemap.ts: all 30 OBC pages
- robots.ts: allow all except /api/
- api/contact/route.ts: OBC devis email template

https://claude.ai/code/session_01Uec4iHjcPwB1pU41idWEdF

app/globals.css

@@ -10,6 +10,10 @@
   --color-orange-hover: #D06522;
   --color-orange-light: #F5A623;
 
+  --color-stone: #8B7355;
+  --color-stone-light: #C4A882;
+  --color-stone-bg: #F5F0EA;
+
   --color-bg: #F7F8FA;
   --color-bg-white: #FFFFFF;
   --color-bg-card: #FFFFFF;
@@ -26,8 +30,8 @@
   --color-warning: #F59E0B;
   --color-error: #EF4444;
 
-  --color-primary: #6D5EF6;
-  --color-primary-hover: #5B4FDB;
+  --color-primary: #E8772E;
+  --color-primary-hover: #D06522;
 
   --color-dark: #0B0F19;
   --color-dark-bg: #0B0F19;