Authenticate with a seeded operator key; fold escalation and switches into TerdutTeam

Credentials: the TerdutServer controller generates <name>-operator-key in
the server's own namespace (owned by it) and hands it to the pods as
TERDUT_OPERATOR_KEY; the server creates its instance-scoped account from it
at every start. A replaced Secret rolls the pods. The bootstrap handshake,
the checkpoint Secret, per-team service accounts and credentials Secrets,
BootstrapStateLost and credentials.deletionPolicy are gone.

CRDs: TerdutServer, TerdutTeam and TerdutAlertSource. TerdutEscalationRule
and TerdutDeadmanSwitch become spec.escalation and spec.deadmanSwitches[]
on the team (matched by name, extras removed); team invites are removed.
A team is created under the identity <namespace>/<name> (external_id), so a
retry, a lost status or a deleted team heal by repeating the same call, and
a display name owned by another team is TeamNameTaken instead of an
adoption. The server resolves escalation usernames (UnknownUser condition).
OIDC claim names and trustEmail are spec fields.

Fixes: query values are URL-escaped; every delete treats 404 as success;
deleting a team no longer depends on allowedTeams consent; a switch or
integration deleted on the server is recreated; unnamed switches take the
CR's name.

Cleanup: scaffold e2e test, AGENTS.md, devcontainer, unused config/ pieces
and Client.Version() removed; DESIGN.md, README, ROADMAP and the demo
(run-demo.sh, manifests) rewritten for the new design. Secret RBAC stays
cluster-wide, now stated in DESIGN.md section 9.

Claude-Session: https://claude.ai/code/session_016mBLURvJoMuUEr9cB2RpUN

config/network-policy/allow-metrics-traffic.yaml

@@ -1,26 +0,0 @@
-# Allow metrics traffic from pods in namespaces labeled 'metrics: enabled'.
-# Add this label to namespaces whose pods should scrape metrics.
-apiVersion: networking.k8s.io/v1
-kind: NetworkPolicy
-metadata:
-  labels:
-    app.kubernetes.io/name: terdut-operator
-    app.kubernetes.io/managed-by: kustomize
-  name: allow-metrics-traffic
-  namespace: system
-spec:
-  podSelector:
-    matchLabels:
-      control-plane: controller-manager
-      app.kubernetes.io/name: terdut-operator
-  policyTypes:
-    - Ingress
-  ingress:
-    # Allow pods in namespaces labeled 'metrics: enabled' to scrape metrics.
-    - from:
-      - namespaceSelector:
-          matchLabels:
-            metrics: enabled  # Only from namespaces with this label
-      ports:
-        - port: 8443
-          protocol: TCP