Polish README with badges and mermaid diagrams, add release infrastructure

Rewrite README with centered header, shields.io badges, mermaid topology
and session key diagrams, restructured installation section with Windows
quick start guide, and release documentation.

Add CHANGELOG.md for v0.2.0 and Gitea Actions release workflow that
builds source archives (tar.gz + zip) and publishes them on tag push.

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

.gitea/workflows/release.yml

@@ -0,0 +1,81 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Extract version from tag
+        id: version
+        run: echo "VERSION=${GITHUB_REF_NAME#v}" >> "$GITHUB_OUTPUT"
+
+      - name: Build source archives
+        run: |
+          PROJECT="claude-statusline-${{ steps.version.outputs.VERSION }}"
+
+          # Files to include in the release archives
+          INCLUDE=(
+            statusline.js
+            fetch-usage.js
+            install.sh
+            install.ps1
+            install_wizard.py
+            package.json
+            requirements.txt
+            README.md
+            CHANGELOG.md
+            LICENSE
+            .gitattributes
+            claude_usage_widget/__init__.py
+            claude_usage_widget/__main__.py
+            claude_usage_widget/app.py
+            claude_usage_widget/config.py
+            claude_usage_widget/fetcher.py
+            claude_usage_widget/menu.py
+            claude_usage_widget/renderer.py
+          )
+
+          mkdir -p "dist/${PROJECT}/claude_usage_widget"
+
+          for f in "${INCLUDE[@]}"; do
+            [ -f "$f" ] && cp "$f" "dist/${PROJECT}/$f"
+          done
+
+          # tar.gz for Linux / macOS
+          tar -czf "dist/${PROJECT}.tar.gz" -C dist "${PROJECT}"
+
+          # zip for Windows
+          cd dist && zip -r "${PROJECT}.zip" "${PROJECT}" && cd ..
+
+      - name: Create release and upload assets
+        env:
+          TAG: ${{ github.ref_name }}
+          VERSION: ${{ steps.version.outputs.VERSION }}
+          TOKEN: ${{ secrets.RELEASE_TOKEN }}
+          GITEA_URL: ${{ github.server_url }}
+          REPO: ${{ github.repository }}
+        run: |
+          API="${GITEA_URL}/api/v1/repos/${REPO}"
+
+          # Create the release
+          RELEASE_ID=$(curl -s -X POST "${API}/releases" \
+            -H "Authorization: token ${TOKEN}" \
+            -H "Content-Type: application/json" \
+            -d "{\"tag_name\":\"${TAG}\",\"name\":\"${TAG}\",\"body\":\"See [CHANGELOG.md](CHANGELOG.md) for details.\",\"draft\":false,\"prerelease\":false}" \
+            | python3 -c "import sys,json; print(json.load(sys.stdin)['id'])")
+
+          # Upload archives
+          for file in dist/claude-statusline-${VERSION}.tar.gz dist/claude-statusline-${VERSION}.zip; do
+            FILENAME=$(basename "$file")
+            curl -s -X POST "${API}/releases/${RELEASE_ID}/assets?name=${FILENAME}" \
+              -H "Authorization: token ${TOKEN}" \
+              -H "Content-Type: application/octet-stream" \
+              --data-binary "@${file}"
+          done