feat(website): partner program page + reseller conversion sections

Add the /partners page rendering the partner pitch: benefits, an interactive
margin calculator (seats × margin → monthly/annual, off the 49 kr list price),
a reseller-facing "CSP vs Dezky" comparison, partner tiers, a 3-step "get
started", and a partner FAQ. Wire the section-06 "see the partner program"
button to it, and align the whitelabel margin bullet to 15–40%.

apps/website/utils/landingCopy.ts

@@ -77,7 +77,7 @@ export const COPY = {
       bullets: [
         'Fuldt whitelabel-tema · CSS og logo',
         'Multi-tenant administration',
-        'Marginer på 30–45 % afhængigt af volumen',
+        'Marginer på 15–40 % afhængigt af volumen',
         'Co-marketing og kundeleads via partnernetværk',
       ],
       cta: 'Se partnerprogrammet',
@@ -363,7 +363,7 @@ export const COPY = {
       bullets: [
         'Full whitelabel theme · CSS and logo',
         'Multi-tenant administration',
-        'Margins of 30–45% by volume',
+        'Margins of 15–40% by volume',
         'Co-marketing and leads via partner network',
       ],
       cta: 'See the partner program',