feat: initial harness spec v1.0.0 + reference template

Adds the normative contract every platform agent must conform to, plus a
working reference template under template/ that ticks every box out of
the box.

Spec is derived from the production agents shipped in
cjot-backstage-az/agents/ on branch sandbox/jonathan:
  - agent-registry, agent-factory, decomposer, discovery-agent,
    golden-path, modernization-factory, modernization-factory-v2,
    policy-transformer, scaffold-agent, support-intake-agent, the-watcher

Contents:
  - SPEC.md          normative contract (13 sections + conformance checklist)
  - CHANGELOG.md     spec versioning (1.0.0)
  - docs/
      registration.md   self-registration with the agent-gateway
      observability.md  OTel logs/metrics/traces wiring
      manifest.md       /.well-known/agent.json schema + AgentSkill
                        serialisation (pydantic vs protobuf)
      kubernetes.md     k8s deployment shape, mandatory cross-refs,
                        per-namespace agents, resource sizing
      deployment.md     .image-version, ACR build, deploy scripts, rollback
      deviations.md     tracked debts against the spec
  - template/
      .env.local.example, .gitignore, .image-version (0.1.0),
      Dockerfile (python:3.12-slim, non-root UID 1001, HEALTHCHECK),
      requirements.txt (harness floor + optional LLM stack),
      app/agent.py (Starlette entry, lifespan + self-registration,
                    defensive _skill_dict for pydantic vs protobuf),
      app/logging_setup.py (canonical OTel log bridge — copy verbatim),
      app/metrics.py (meter + example counter/histogram),
      app/skills.py (AGENT_CONFIG + AgentSkill list),
      k8s/configmap.yaml + deployment.yaml (Deployment + Service,
                                            OTel annotations + 6-var env block,
                                            agents-sa + agents-kv-spc bindings),
      scripts/deploy.sh (auto-bump + az acr build + apply + rollout),
      scripts/full-deploy.sh (preflight + deploy + post-deploy smoke),
      scripts/deploy-local.sh (docker/podman + .env.local)

template/app/metrics.py

@@ -0,0 +1,33 @@
+"""OTel metric instruments for <agent-name>.
+
+All metrics flow through the global MeterProvider installed by the OTel
+Operator's init container. The provider exports OTLP to the cluster tier-1
+collector, which forwards metrics to Prometheus via tier-2's remote-write.
+
+Naming convention (see SPEC §7.4):
+
+    agent.<agent_type>.<noun>            — counters (unit="1")
+    agent.<agent_type>.<noun>.duration   — histograms in seconds (unit="s")
+
+Replace `<agent_name>` and the example instruments with your own.
+"""
+from __future__ import annotations
+
+from opentelemetry import metrics
+
+# The (name, version) pair becomes `otel_scope_name` and `otel_scope_version`
+# attributes on every metric — useful for filtering in PromQL.
+_meter = metrics.get_meter("<agent-name>", "0.1.0")
+
+# ─── Example: an "echo" operation counter and latency histogram ─────────
+echoes = _meter.create_counter(
+    "agent.<agent_name>.echoes",
+    unit="1",
+    description="Echo requests by outcome.",
+)
+
+echo_duration = _meter.create_histogram(
+    "agent.<agent_name>.echo.duration",
+    unit="s",
+    description="End-to-end /echo latency.",
+)