feat: extend Flux image automation, Gatus, and docs for VIN Decoder

Closes leeworks-agents/api-company#133
Closes leeworks-agents/api-company#134
Closes leeworks-agents/api-company#135
Closes leeworks-agents/api-company#136

- flux/image-automation/imagerepositories.yaml: add vin-decoder ImageRepository
  pointing at registry.leeworks.dev/vin-decoder/api (#133)
- flux/image-automation/imagepolicies.yaml: add vin-decoder ImagePolicy
  with semver range >=0.1.0 (#133)
- flux/monitoring/gatus-helmrelease.yaml: add VIN Decoder API endpoint check
  targeting https://vin.leeworks.dev/v1/health with Slack alert (#134)
- docs/pre-launch-checklist.md: add vin-decoder to Infrastructure, DNS & TLS,
  Functional Verification, and Legal sections; update status page line to
  reference all four APIs (#135)
- docs/secrets-checklist.md: add items #11-13 for vin-decoder GITEA_TOKEN,
  gitea-registry, and rapidapi-proxy-secret; add detail sections for each (#136)

kustomize build flux/ passes with zero errors.

flux/monitoring/gatus-helmrelease.yaml

@@ -68,6 +68,15 @@ spec:
               description: "Air Quality API is down"
               send-on-resolved: true
 
+
+        - name: VIN Decoder API
+          url: https://vin.leeworks.dev/v1/health
+          interval: 1m
+          conditions:
+            - "[STATUS] == 200"
+            - "[RESPONSE_TIME] < 1000"
+          alerts:
+            - type: slack
         - name: Docs Site
           url: https://docs.leeworks.dev
           interval: 5m