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/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,29 @@
+---
+name: Bug report
+about: Report something that isn't working
+title: "[Bug] "
+labels: bug
+---
+
+**Describe the bug**
+A clear description of what's wrong.
+
+**To reproduce**
+Steps to reproduce the behavior:
+1. …
+2. …
+
+**Expected behavior**
+What you expected to happen.
+
+**Screenshots / logs**
+If applicable, add screenshots or server log output.
+
+**Environment**
+- ADS-Bit version (admin header or `GET /api/config`):
+- Install method: [ ] bare metal  [ ] Docker  [ ] Podman
+- OS / Python version:
+- Receiver / feed (e.g. dump1090, readsb) and how it's reached:
+
+**Additional context**
+Anything else that might help.