feat(repo)!: repo reorganization (#16)

* feat(repo)!: restructure around the dsh-harness image and one example per implementation

- the root Dockerfile is the primary artifact; versions.env is the single source of truth
- merge gateway-api/dsh-demo into examples/dsh-agents-as-a-service (manifests/, exposure variants)
- move the single-tenant template into examples/minimal-single-tenant
- publish the gateway as a nested package under the repository image
- mirror the DSH ref for release identities (first release dsh-v0.2.1-rc.2-r2)
- CI: lint/python/manifests/gateway-image, reusable multi-arch build, tag-driven release, weekly e2e
- docs: README, docs/{main-image,examples,gitflow,versioning}, example READMEs, AGENTS.md, governance
- SSO is opt-in again; gateway pull policy and cookie defaults match the documented demo

BREAKING CHANGE: example manifest paths, the gateway image name, and the removal
of deploy/ and gateway-api/ affect existing deployments; see the migration table
in README.md.

* docs(changelog): generate initial changelog from history

* fix(scripts): make set-version update Dockerfile and sample revision pins

* build(hadolint): document intentional lint exceptions for the main image

---------

Co-authored-by: SREDevOpsAgents <agents@sredevops.org>

SECURITY.md

@@ -0,0 +1,41 @@
+# Security policy
+
+## Supported versions
+
+Only the latest published release is supported. Image tags are immutable;
+fixes ship as a new release (see docs/versioning.md).
+
+## Reporting a vulnerability
+
+Report vulnerabilities privately through GitHub Security Advisories:
+
+https://github.com/sredevopsorg/deepseek-kubernetes-sandbox/security/advisories/new
+
+Do not open a public issue, and do not include live credentials in a report.
+You can expect an acknowledgement within a few days and a coordinated
+disclosure once a fix is available.
+
+## Threat notes specific to this project
+
+- **Launch token in pod logs.** The example gateway reads DSH's launch token
+  from pod logs (pods/log). Anyone with access to those logs can impersonate a
+  tenant. Keep the gateway's RBAC namespace-scoped and treat pod logs as
+  sensitive. Replacing log scraping with an upstream token API is tracked in
+  the example architecture document.
+- **SSO header trust boundary.** AUTH_PROXY_HEADER makes the gateway trust an
+  identity header (for example X-Forwarded-User). Enable it only when the
+  gateway Service is reachable exclusively through the authenticating proxy;
+  otherwise any client can spoof the header.
+- **Shared provider key.** The example injects one DEEPSEEK_API_KEY into every
+  tenant sandbox (a warm-pool constraint). Treat tenants as mutually trusting
+  until per-tenant credentials or an egress proxy exist.
+- **TLS is external.** Terminate TLS at an Ingress or Gateway and set
+  COOKIE_SECURE=true. Plain HTTP outside localhost exposes session cookies.
+- **No secrets in the repository.** The repository only ships empty Secret
+  manifests and *.yaml.example files.
+
+## Dependency and supply chain
+
+GitHub Actions are pinned by commit SHA. The CodeQL workflow scans Python and
+Actions. The release workflow publishes images with SBOM and provenance
+attestations.