Package for public GitHub release

Add open-source scaffolding and CI; remove Claude-specific dev notes from the
published tree.

- Remove CLAUDE.md from tracking (kept locally, now git-ignored).
- CHANGELOG.md (Keep a Changelog; v1.0 → v1.1.1).
- SECURITY.md (private vuln reporting + operator guidance).
- CONTRIBUTING.md (dev setup, conventions, PR flow).
- .github/: bug + feature issue templates, PR template.
- .github/workflows/ci.yml: byte-compile, validate example config, docker build.
- .github/workflows/release.yml: on a version tag, publish a multi-arch
  (amd64 + arm64) image to GHCR.
- README: license/release/CI badges, prebuilt-image (GHCR) run instructions,
  and a corrected Python-version note (3.9–3.11; netifaces caveat).

Badges and image names use an `OWNER` placeholder to replace with the GitHub
namespace after the repo is created.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -0,0 +1,30 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  python:
+    name: Python checks
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+      - name: Install dependencies
+        run: pip install -r requirements.txt
+      - name: Byte-compile server
+        run: python -m compileall -q server.py
+      - name: Validate example config is valid JSON
+        run: python -c "import json; json.load(open('config.json.example'))"
+
+  docker:
+    name: Docker build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build image
+        run: docker build -t ads-bit:ci .