grid-site chart: minimal install (only required name fields) fails with "spec: Required value"

[jordigilh]

Summary

A minimal grid-site chart install — using only the two fields required by
values.schema.json (gridNetwork.name, gridSite.name) and leaving every
other gridNetwork.* value at its chart default — is rejected by the
Kubernetes API server:

The GridNetwork "prod-grid" is invalid: spec: Required value

This reproduces identically on main (confirmed via
git archive origin/main -- charts/grid-site rendered against a live Kind
cluster with kubectl create --dry-run=server), so it is not specific to
any in-flight feature branch.

Root cause

charts/grid-site/templates/gridnetwork.yaml gates every single
GridNetwork.spec field behind a Helm {{- with ... }} block:
gridId, region, zone, routingPolicy, scoringPolicy,
metricsRefreshInterval, swim, tls, gatewayRefs. The chart's
values.yaml defaults for all of these are falsy ("", {}, or []), which
Go's text/template with treats as "absent" — so when none of them are
overridden, the rendered spec: has no children at all:

spec:

That's YAML null, not an empty object ({}). The GridNetwork CRD's
structural schema requires spec to be present as an object, so the API
server rejects both a fresh helm install and any helm upgrade that lands
on this all-defaults state (e.g. removing the last non-default field, such as
budgetPolicy, from an existing release).

Impact

Any consumer following the chart's own documented minimal usage (set only the
two required name fields) cannot install grid-site today. This was caught
while live-validating grid#47 (tenant-budget plumbing) on a Kind cluster on
helios08 — unsetting budgetPolicy via helm upgrade was the reproduction
path, but the bug pre-dates that PR and affects any all-defaults install.

Fix

Fixed alongside grid#47: gridId is now rendered unconditionally
(gridId: {{ .Values.gridNetwork.gridId | quote }}, defaulting to "",
which is already a valid/expected value per the CRD's own server-side
default) instead of being gated behind with. This guarantees spec always
has at least one key, so it's never null. A helm-unittest regression case
("renders a non-null spec when only the required name fields are set") was
added to charts/grid-site/tests/gridnetwork_test.yaml.

Verified live on a Kind cluster (helios08):

• Before fix: kubectl create --dry-run=server on the minimal-fields render → spec: Required value.
• After fix: same dry-run → gridnetwork.grid.praxis-proxy.io/zz-fresh created (server dry run).
• helm upgrade removing budgetPolicy from an existing release (previously failed with the same error) now succeeds and status.budgetStatus clears back to empty as expected.
• Full KIND=1 ./scripts/verify-helm-chart.sh (182 checks) still passes with no regressions.

See #47 for the fix commit.