ci: optimize workflow performance

- PR docker builds use single arch (amd64 only), tag push uses dual
- Add paths-ignore to skip CI on docs-only changes
- Add concurrency groups to cancel stale runs on re-push
- Build Go binary once instead of 3x go run in migrate job

.github/workflows/ci.yml

@@ -3,8 +3,20 @@ name: CI
 on:
   push:
     branches: [main]
+    paths-ignore:
+      - "docs/**"
+      - "**.md"
+      - "devenv/**"
   pull_request:
     branches: [main]
+    paths-ignore:
+      - "docs/**"
+      - "**.md"
+      - "devenv/**"
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
 
 permissions:
   contents: read
@@ -33,6 +45,9 @@ jobs:
         with:
           go-version-file: go.mod
 
+      - name: Build
+        run: go build -o memoh-server ./cmd/agent
+
       - name: Generate config
         run: |
           cat > config.toml <<'TOML'
@@ -46,10 +61,10 @@ jobs:
           TOML
 
       - name: Migrate up
-        run: go run ./cmd/agent migrate up
+        run: ./memoh-server migrate up
 
       - name: Migrate down
-        run: go run ./cmd/agent migrate down
+        run: ./memoh-server migrate down
 
       - name: Migrate up (idempotent)
-        run: go run ./cmd/agent migrate up
+        run: ./memoh-server migrate up

.github/workflows/docker-publish.yml

@@ -5,8 +5,16 @@ on:
     tags: ["v*.*.*"]
   pull_request:
     branches: [main]
+    paths-ignore:
+      - "docs/**"
+      - "**.md"
+      - "devenv/**"
   workflow_dispatch:
 
+concurrency:
+  group: docker-${{ github.ref }}
+  cancel-in-progress: true
+
 permissions:
   contents: read
   packages: write
@@ -78,7 +86,7 @@ jobs:
           push: ${{ startsWith(github.ref, 'refs/tags/') }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-          platforms: linux/amd64,linux/arm64
+          platforms: ${{ startsWith(github.ref, 'refs/tags/') && 'linux/amd64,linux/arm64' || 'linux/amd64' }}
           build-args: |
             VERSION=${{ steps.meta.outputs.version }}
             COMMIT_HASH=${{ github.sha }}