ci: add GitHub Actions workflows mirroring Gitea CI

Add two GitHub Actions workflows as corollaries to the existing
.gitea/workflows/ci.yml pipeline:

- .github/workflows/ci.yml: direct port of the Gitea CI — same 5-stage
  pipeline (lint, composer install, phpcs, phpstan, phpunit) using the
  same docker-based scripts. Triggers on push/PR to main.

- .github/workflows/release.yml: creates a GitHub Release when a semver
  tag (v*.*.* ) is pushed. Builds a distributable plugin ZIP with the
  required root directory name AssignColorsByDayOfWeek (Kanboard plugin
  installer convention). vendor/ is intentionally excluded — this plugin
  has no production Composer dependencies. Uses gh CLI with
  --generate-notes for auto-generated release notes.

Author: geekmuse

.github/workflows/ci.yml

@@ -0,0 +1,48 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      # Stage 1 — PHP syntax check
+      # Uses kanboard/kanboard image with entrypoint override (default entrypoint
+      # starts Apache and runs forever; we override to /bin/sh for one-shot use).
+      - name: Lint — PHP syntax check
+        run: bash scripts/docker-lint.sh
+
+      # Stage 2 — Install Composer dependencies
+      # vendor/ is not committed (.gitignore); install it here so the remaining
+      # stages can find vendor/bin/phpcs, vendor/bin/phpstan, vendor/bin/phpunit.
+      - name: Install Composer dependencies
+        run: |
+          docker run --rm \
+            -v "$PWD":/app \
+            composer:2 \
+            install --no-interaction --prefer-dist --no-progress
+
+      # Stage 3 — PSR-12 code style check
+      - name: PHPCS — PSR-12 style check
+        run: bash scripts/docker-phpcs.sh
+
+      # Stage 4 — Static analysis (PHPStan level 5)
+      # Uses php:8.4-cli — kanboard/kanboard lacks the tokenizer extension
+      # required by PHPStan.
+      - name: PHPStan — static analysis
+        run: bash scripts/docker-phpstan.sh
+
+      # Stage 5 — Unit tests
+      # Uses php:8.4-cli for the same reason as PHPStan above.
+      - name: PHPUnit — unit tests
+        run: bash scripts/docker-test.sh

.github/workflows/release.yml

@@ -0,0 +1,49 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v[0-9]+.[0-9]+.[0-9]+'
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Extract version from tag
+        id: version
+        run: echo "version=${GITHUB_REF_NAME#v}" >> "$GITHUB_OUTPUT"
+
+      # Build a distributable plugin ZIP.
+      # Kanboard's plugin installer expects a ZIP containing a single root
+      # directory named exactly after the plugin class: AssignColorsByDayOfWeek.
+      # This plugin has no production Composer dependencies (require-dev only),
+      # so vendor/ is intentionally excluded from the archive.
+      - name: Build plugin archive
+        run: |
+          ARCHIVE="AssignColorsByDayOfWeek-${{ steps.version.outputs.version }}.zip"
+          PLUGIN_DIR="AssignColorsByDayOfWeek"
+
+          mkdir -p "dist/$PLUGIN_DIR"
+          cp -r Action "dist/$PLUGIN_DIR/"
+          cp Plugin.php LICENSE README.md CHANGELOG.md composer.json "dist/$PLUGIN_DIR/"
+
+          cd dist
+          zip -r "../$ARCHIVE" "$PLUGIN_DIR/"
+          cd ..
+
+          echo "ARCHIVE=$ARCHIVE" >> "$GITHUB_ENV"
+
+      - name: Create GitHub Release
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh release create "${{ github.ref_name }}" \
+            --title "${{ github.ref_name }}" \
+            --generate-notes \
+            "$ARCHIVE"