Add shared docker-tags composite action for multi-channel Docker tag resolution

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-tags/action.yml

@@ -0,0 +1,70 @@
+# Docker Tag Resolver
+# Generates Docker image tags based on branch (dev / next-release / main)
+#
+# Tag strategy:
+#   main          -> latest, <calver>, <calver>-<sha>
+#   next-release  -> next-release, <calver>-rc, <calver>-rc-<sha>
+#   anything else -> dev, dev-<sha>
+
+name: Docker Tags
+description: Resolve Docker image tags based on branch and CalVer version
+
+inputs:
+  image:
+    description: Docker image name (e.g., user/repo)
+    required: true
+  version:
+    description: CalVer version from the calver action
+    required: true
+  sha_short:
+    description: Short commit SHA (7 chars)
+    required: true
+
+outputs:
+  tags:
+    description: Comma-separated list of full image tags
+    value: ${{ steps.resolve.outputs.tags }}
+  channel:
+    description: Release channel (stable, rc, dev)
+    value: ${{ steps.resolve.outputs.channel }}
+  primary_tag:
+    description: The primary human-readable tag (latest, next-release, or dev)
+    value: ${{ steps.resolve.outputs.primary_tag }}
+
+runs:
+  using: composite
+  steps:
+    - name: Resolve Docker tags
+      id: resolve
+      shell: bash
+      run: |
+        IMAGE="${{ inputs.image }}"
+        VERSION="${{ inputs.version }}"
+        SHA="${{ inputs.sha_short }}"
+        BRANCH="${GITHUB_REF_NAME}"
+
+        case "${BRANCH}" in
+          main)
+            TAGS="${IMAGE}:latest,${IMAGE}:${VERSION},${IMAGE}:${VERSION}-${SHA}"
+            CHANNEL="stable"
+            PRIMARY="latest"
+            ;;
+          next-release)
+            TAGS="${IMAGE}:next-release,${IMAGE}:${VERSION}-rc,${IMAGE}:${VERSION}-rc-${SHA}"
+            CHANNEL="rc"
+            PRIMARY="next-release"
+            ;;
+          *)
+            TAGS="${IMAGE}:dev,${IMAGE}:dev-${SHA}"
+            CHANNEL="dev"
+            PRIMARY="dev"
+            ;;
+        esac
+
+        echo "tags=${TAGS}" >> $GITHUB_OUTPUT
+        echo "channel=${CHANNEL}" >> $GITHUB_OUTPUT
+        echo "primary_tag=${PRIMARY}" >> $GITHUB_OUTPUT
+
+        echo "Branch: ${BRANCH}"
+        echo "Channel: ${CHANNEL}"
+        echo "Tags: ${TAGS}"