fix: correct Helm chart port from 8080 to 4321

Updated Helm chart configuration to use the correct application port (4321)
instead of the incorrect default (8080). This aligns the Helm deployment
with the actual application configuration.

Changes:
- helm/gitea-mirror/values.yaml: Updated service.port and deployment.port to 4321
- helm/gitea-mirror/README.md: Updated all port references in documentation
- www/src/pages/use-cases/deploy-with-helm-chart.mdx: Fixed article to reflect
  correct port, added GitHub links to Helm chart, and improved installation instructions

The application runs on port 4321 as defined in:
- Dockerfile (ENV PORT=4321, EXPOSE 4321)
- docker-compose.yml (4321:4321 mapping)
- .env.example (PORT=4321)

Tested with local Kubernetes cluster and confirmed the application is accessible
on port 4321.

helm/gitea-mirror/README.md

@@ -29,7 +29,7 @@ kubectl create namespace gitea-mirror
 helm upgrade --install gitea-mirror ./helm/gitea-mirror   --namespace gitea-mirror   --set "gitea-mirror.github.username=<your-gh-username>"   --set "gitea-mirror.github.token=<your-gh-token>"   --set "gitea-mirror.gitea.url=https://gitea.example.com"   --set "gitea-mirror.gitea.token=<your-gitea-token>"
 ```
 
-The default Service is `ClusterIP` on port `8080`. You can expose it via Ingress or Gateway API; see below.
+The default Service is `ClusterIP` on port `4321`. You can expose it via Ingress or Gateway API; see below.
 
 ---
 
@@ -78,7 +78,7 @@ If you enabled persistence with a PVC the data may persist; delete the PVC manua
 
 | Key | Type | Default | Description |
 | --- | --- | --- | --- |
-| `deployment.port` | int | `8080` | Container port & named `http` port. |
+| `deployment.port` | int | `4321` | Container port & named `http` port. |
 | `deployment.strategy.type` | string | `Recreate` | Update strategy (`Recreate` or `RollingUpdate`). |
 | `deployment.strategy.rollingUpdate.maxUnavailable/maxSurge` | string/int | — | Used when `type=RollingUpdate`. |
 | `deployment.env` | list | `[]` | Extra environment variables. |
@@ -95,7 +95,7 @@ If you enabled persistence with a PVC the data may persist; delete the PVC manua
 | Key | Type | Default | Description |
 | --- | --- | --- | --- |
 | `service.type` | string | `ClusterIP` | Service type. |
-| `service.port` | int | `8080` | Service port. |
+| `service.port` | int | `4321` | Service port. |
 | `service.clusterIP` | string | `None` | ClusterIP (only when `type=ClusterIP`). |
 | `service.externalTrafficPolicy` | string | `""` | External traffic policy (LB). |
 | `service.loadBalancerIP` | string | `""` | LoadBalancer IP. |
@@ -228,7 +228,7 @@ ingress:
         - mirror.example.com
 ```
 
-This creates an Ingress routing `/` to the service on port `8080`.
+This creates an Ingress routing `/` to the service on port `4321`.
 
 ### Using Gateway API (HTTPRoute)
 
@@ -257,7 +257,7 @@ By default, the chart provisions a PVC named `gitea-mirror-storage` with `1Gi` a
 
 ## Environment & health endpoints
 
-The container listens on `PORT` (defaults to `deployment.port` = `8080`) and exposes `GET /api/health` for liveness/readiness/startup probes.
+The container listens on `PORT` (defaults to `deployment.port` = `4321`) and exposes `GET /api/health` for liveness/readiness/startup probes.
 
 ---
 

helm/gitea-mirror/values.yaml

@@ -46,7 +46,7 @@ route:
 
 service:
   type: ClusterIP
-  port: 8080
+  port: 4321
   clusterIP: None
   annotations: {}
   externalTrafficPolicy:
@@ -55,7 +55,7 @@ service:
   loadBalancerClass:
 
 deployment:
-  port: 8080
+  port: 4321
   strategy:
     type: Recreate
   env: []