add SemVer release process with automated publishing

- Split workflows: CI (lint/validate) and Docker (dev builds)
- Add release.yml for versioned releases with manual trigger
- Release workflow creates release/<version> branches, updates version.py, builds Docker images with SemVer tags, and creates GitHub releases
- Docker images tagged as major.minor.patch, major.minor, major, latest for stable releases
- Pre-release versions tagged with exact version only

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.github/workflows/docker.yml

@@ -0,0 +1,62 @@
+name: Docker Dev Build
+
+on:
+  push:
+    branches:
+      - main
+      - master
+      - develop
+  workflow_dispatch:
+
+jobs:
+  docker:
+    name: Docker Dev Build & Push
+    runs-on: ubuntu-latest
+    environment: prod
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v5
+
+      - name: Set up variables
+        id: vars
+        run: |
+          echo "sha_short=$(git rev-parse --short HEAD)" >> "${GITHUB_OUTPUT}"
+          echo "date=$(date +%Y-%m-%d)" >> "${GITHUB_OUTPUT}"
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Extract metadata for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: rangermix/twitch-drops-miner
+          tags: |
+            type=raw,value=dev
+            type=raw,value=dev-${{steps.vars.outputs.sha_short}}
+            type=raw,value=latest,enable=${{github.ref == 'refs/heads/master'}}
+            type=sha,prefix=
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{steps.meta.outputs.tags}}
+          labels: ${{steps.meta.outputs.labels}}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+          build-args: |
+            BUILD_DATE=${{steps.vars.outputs.date}}
+            VCS_REF=${{github.sha}}
+            VERSION=dev-${{steps.vars.outputs.sha_short}}