feat(homepage): expand inline lead form to name/email/phone/type/message

Rework the homepage InlineLeadForm from a single combined "email or phone"
contact field to an explicit 5-field layout — name, email (type=email),
phone (type=tel), project type and an optional message — so each field gets
the correct mobile keyboard and leads carry a real email + phone separately.

- Required fields kept to name + email + project type for a low-friction
  mobile flow; phone and message are optional.
- Email uses type=email + inputmode=email; phone uses type=tel + inputmode=tel
  for the numeric keypad. Message is an optional textarea; when blank the
  client synthesizes a >=10 char summary so the /api/contact validator passes.
- Still posts to the same /api/contact endpoint tagged source=homepage-inline,
  delivering leads exactly the same way the /contact page does (no page nav).
- Update inline-lead-form.spec.ts to the new field set and keyboards.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/pages/index.astro

@@ -744,9 +744,11 @@ const techStack = [
 
   <!-- Inline Lead Form — sits between the tech-stack social-proof block
        and the final CTA band so visitors who are ready to start a project can
-       submit a 3-field enquiry without leaving the homepage. Submits to the
-       same /api/contact endpoint and is tagged `source: 'homepage-inline'` so
-       the lead can be segmented downstream. -->
+       submit a compact enquiry (name, email, phone, project type, message)
+       without leaving the homepage. Required fields are kept to name + email +
+       project type for a low-friction mobile flow. Submits to the same
+       /api/contact endpoint and is tagged `source: 'homepage-inline'` so the
+       lead can be segmented downstream. -->
   <InlineLeadForm />
 
   <!-- Homepage FAQ — single canonical FAQ section for /. Covers the cost /