refactor: rebrand from net.siegeln to io.cameleer

Institutionalize the product identity ahead of public release:

- Java package: net.siegeln.cameleer.saas → io.cameleer.saas (109 files)
- Maven groupId: net.siegeln.cameleer → io.cameleer
- Public image defaults: gitea.siegeln.net/cameleer/ → registry.cameleer.io/cameleer/
- Updated docs (architecture, user-manual, HOWTO, runtime-loader README)
- Updated CLAUDE.md path references

Internal build infra (CI workflows, .gitmodules, npm registry, Maven repo)
intentionally kept at gitea.siegeln.net — code stays on internal Gitea.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

HOWTO.md

@@ -444,4 +444,4 @@ VERSION=local docker compose -f docker-compose.yml -f docker-compose.dev.yml up
 
 **Ephemeral key warnings**: `No Ed25519 key files configured -- generating ephemeral keys (dev mode)` is normal in development. For production, generate keys as described above.
 
-**Container deployment fails**: Check that Docker socket is mounted (`/var/run/docker.sock`) and the `cameleer-runtime-base` image is available. Pull it with: `docker pull gitea.siegeln.net/cameleer/cameleer-runtime-base:latest`
+**Container deployment fails**: Check that Docker socket is mounted (`/var/run/docker.sock`) and the `cameleer-runtime-base` image is available. Pull it with: `docker pull registry.cameleer.io/cameleer/cameleer-runtime-base:latest`