docs: add VIN Decoder listing copy and dns.md entry

Closes leeworks-agents/api-company#131
Closes leeworks-agents/api-company#130

- docs/rapidapi-listings.md: add Section 4 — VIN Decoder API with
  title, tagline, short/long description, tier table (Free/Basic/Pro/Ultra),
  endpoint descriptions, and keywords. Mirrors style of existing three
  API sections. Tiers match the spec from issue #131.
- docs/dns.md: add vin.leeworks.dev as 8th subdomain in records table,
  verification dig command, action-required count (7→8), and status
  checklist entry. Updated last-updated date to 2026-05-30.

docs/dns.md

@@ -1,6 +1,6 @@
 # DNS Configuration
 
-**Last updated:** 2026-05-24  
+**Last updated:** 2026-05-30  
 **Status:** Planned (Phase 6 pre-launch)
 
 ---
@@ -28,6 +28,7 @@ kubectl get svc -n ingress-nginx ingress-nginx-controller -o jsonpath='{.status.
 | `status.leeworks.dev` | A | `<cluster-ingress-ip>` | Gatus status page | Yes (cert-manager) |
 | `registry.leeworks.dev` | A | `<cluster-ingress-ip>` | Container registry (Gitea) | Yes (cert-manager) |
 | `grafana.leeworks.dev` | A | `<cluster-ingress-ip>` | Grafana (internal/restricted) | Yes (cert-manager) |
+| `vin.leeworks.dev` | A | `<cluster-ingress-ip>` | VIN Decoder API | Yes (cert-manager) |
 
 ---
 
@@ -103,6 +104,7 @@ dig docs.leeworks.dev +short
 dig status.leeworks.dev +short
 dig registry.leeworks.dev +short
 dig grafana.leeworks.dev +short
+dig vin.leeworks.dev +short
 
 # Check TLS certificates (once services are deployed)
 curl -v https://zip.leeworks.dev/health 2>&1 | grep -E "SSL|certificate|issuer"
@@ -126,7 +128,7 @@ The following actions require human operator access to the DNS provider:
 
 1. Log into the DNS provider managing `leeworks.dev`
 2. Find the cluster ingress IP: `kubectl get svc -n ingress-nginx ingress-nginx-controller`
-3. Create/update the 7 A records listed in the table above
+3. Create/update the 8 A records listed in the table above
 4. Verify propagation: `dig +trace zip.leeworks.dev`
 
 DNS propagation typically takes 5–60 minutes.
@@ -143,4 +145,5 @@ DNS propagation typically takes 5–60 minutes.
 - [ ] `status.leeworks.dev` → DNS record created
 - [ ] `registry.leeworks.dev` → DNS record created
 - [ ] `grafana.leeworks.dev` → DNS record created
-- [ ] TLS certificates issued and valid for all 7 subdomains
+- [ ] `vin.leeworks.dev` → DNS record created
+- [ ] TLS certificates issued and valid for all 8 subdomains