fix(vpn-ingress): content-hash the peer register, or a merged peer never reaches the tunnel

The operator enrolled a phone, merged the peer, and `wg show` listed none.
Measured on prod 2026-10-06 with the peer already on main:

  live wg-peers ConfigMap, active AllowedIPs .. 0
  DaemonSet volume reference ................. configMap.name: wg-peers (FIXED)
  DaemonSet generation/observedGeneration .... 1 / 1   (never rolled)
  init container, all three pods ............. "0 peer(s)"

Part of it was just the 10m reconcile interval. The defect is the fixed name:
Flux updates a fixed-name ConfigMap IN PLACE, so the pod template is
byte-identical, so no rollout is triggered -- and the init container assembles
wg0.conf ONCE at pod start into a tmpfs, so the running tunnel keeps the old
peer list indefinitely. Adding or revoking a peer had no effect until something
unrelated restarted the pods. For a REVOCATION that is a security defect, not
an inconvenience: delete a stanza, see a green PR, device keeps working.

The runbook and README both claimed "PR -> merge -> Flux rolls the DaemonSet".
Never true. And this repo already documents the fix, in a file I had read --
runbooks/kustomization.yaml: "The generated name carries kustomize's content
hash, so editing any runbook rolls the server automatically and a stale
projection is impossible."

So: peers.yaml (inline ConfigMap) -> peers.conf (plain file) + a
configMapGenerator. The operator's enrolled peer is carried across verbatim.
Every line is WireGuard config and `#` is a legal comment there, so the
documentation now lives inside the file that is actually mounted.

`namespace: vpn-ingress` on the kustomization is REQUIRED, not tidiness: a
generated ConfigMap inherits no namespace, everything else here declares
vpn-ingress, and kustomize's nameReference will not rewrite across a namespace
boundary -- without it the build mounts the unhashed name and the pods wedge on
a missing volume. Caught only by building the output and reading the volumes.

new-peer.sh: PEERS_FILE repointed, and a missing register is now FATAL rather
than skipped -- the old `[ -r "$PEERS_FILE" ] && grep ...` guard meant that
after the rename the only symptom would have been duplicate detection quietly
never firing again. Stale peers.yaml references swept from six files including
the script's own user-facing output.

Verified: the DaemonSet now mounts wg-peers-m9kcckcb5t; the hash tracks content
(edit -> dgg7ht9c74 -> restore -> m9kcckcb5t); the enrolled peer is byte-identical
to main's; and `new-peer.sh dupe 2` is now correctly refused by the operator's
real allocation.

No sensitive paths; merges on a green gate.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

platform/vpn-ingress/networkpolicy.yaml

@@ -19,7 +19,7 @@
 # protects this port, and it would be enforcing nothing. So there isn't one.
 #
 # WHAT ACTUALLY PROTECTS THE EXPOSED PORT, then, since the CNI does not:
-#   1. WireGuard's cryptographic peer authentication. A packet whose key is not in peers.yaml gets
+#   1. WireGuard's cryptographic peer authentication. A packet whose key is not in peers.conf gets
 #      NO REPLY — see README "Why this is safe to expose". This is the real control.
 #   2. The SOHO router's forward: only udp/51820 is forwarded inbound, to one node.
 #   3. The blast radius once authenticated is deliberately the whole LAN — that IS the requirement