Set kubernetes backend options on all woodpecker steps

Give every CI step explicit resource requests/limits and the default service
account (matching the pre-commit step), so the k8s woodpecker backend schedules
them with bounded resources.

- build/test/lint/package steps: 512Mi/1cpu requests, 2Gi/2cpu limits
- upload step: lighter 128Mi/100m requests, 512Mi/500m limits

.woodpecker/build.yml

@@ -6,3 +6,13 @@ steps:
     image: golang:1.25
     commands:
       - make build
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2

.woodpecker/release.yml

@@ -6,12 +6,32 @@ steps:
     image: git.unkin.net/unkin/almalinux9-gobuilder:20260606
     commands:
       - make build VERSION=${CI_COMMIT_TAG}
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2
 
   - name: package
     image: git.unkin.net/unkin/almalinux9-rpmbuilder:latest
     commands:
       - ./scripts/build-rpm.sh ${CI_COMMIT_TAG}
     depends_on: [build]
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2
 
   - name: upload
     image: git.unkin.net/unkin/almalinux9-base:20260606
@@ -36,3 +56,13 @@ steps:
             --data-binary @"$$rpm"
         done
     depends_on: [package]
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 128Mi
+            cpu: 100m
+          limits:
+            memory: 512Mi
+            cpu: 500m

.woodpecker/test.yml

@@ -6,8 +6,28 @@ steps:
     image: golang:1.25
     commands:
       - make lint
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2
 
   - name: test
     image: golang:1.25
     commands:
       - make test
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2