Stop forcing DOCKER_HOST to tcp://docker.local:2375

Job containers already mount the host Docker socket and default to
unix:///var/run/docker.sock. The TCP override is unreachable from the
bridge network and breaks docker login/build in Gitea Actions.

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitea/actions/docker-build/action.yml

@@ -1,5 +1,5 @@
 name: Docker Build + Push
-description: Build and push Docker images for Gitea Actions using the docker daemon at DOCKER_HOST
+description: Build and push Docker images for Gitea Actions via the job-mounted Docker socket
 author: eric
 
 inputs:
@@ -44,9 +44,6 @@ outputs:
 
 runs:
   using: composite
-  env:
-    DOCKER_HOST: tcp://docker.local:2375
-    DOCKER_BUILDKIT: "1"
 
   steps:
     - name: Compute metadata
@@ -77,6 +74,8 @@ runs:
 
     - name: Log in to Docker registry
       shell: bash
+      env:
+        DOCKER_BUILDKIT: "1"
       run: |
         if [ -n "${{ inputs.registry }}" ] && [ -n "${{ inputs.registry-password }}" ]; then
           echo "${{ inputs.registry-password }}" | docker login ${{ inputs.registry }} -u ${{ inputs.registry-username }} --password-stdin
@@ -85,6 +84,8 @@ runs:
     - name: Build image
       id: build
       shell: bash
+      env:
+        DOCKER_BUILDKIT: "1"
       run: |
         BUILD_ARGS_FLAG=""
         if [ -n "${{ inputs.build-args }}" ]; then