fix(crd): make vlanInterfaces item validation actually take effect

[oilbeater]

What

ProviderNetwork.Spec.VlanInterfaces carried this marker:

// +kubebuilder:validation:Items={Type=string,Pattern=`^[a-zA-Z0-9_-]+\\.[0-9]{1,4}$`}

Items={...} is not a marker controller-gen recognises, so it was silently
dropped. The generated CRD ships a bare items: {type: string} — the field
accepts any string today.

The pattern was wrong too: inside a Go raw string literal \\. is a literal
backslash followed by any character, not an escaped dot, so the expression
rejects every legal value such as eth0.10. Fixing only the marker name
would have turned a silent no-op into a hard regression — worth knowing for
anyone reviewing similar markers.

Change

Use the items: marker prefix controller-gen supports, escape the dot once,
and cap the length at IFNAMSIZ-1 to match defaultInterface and
customInterfaces[].interface:

// +kubebuilder:validation:items:Pattern=`^[a-zA-Z0-9_-]+\.[0-9]{1,4}$`
// +kubebuilder:validation:items:MaxLength=15

Regenerated CRDs via make gen-crd (charts v1/v2 + install.sh).

Why this shape

The pattern encodes exactly what the daemon accepts. createVlanSubinterfaces
splits the name on the first dot and requires the parent to match the provider
network's default interface, and ExtractVlanIDFromInterface derives the VLAN
ID from the suffix. A name the daemon cannot parse is only reported as a
klog.Warningf and then skipped, so today a typo in this field is invisible to
the user — the resource is accepted and the interface is silently never
programmed.

Validation

Checked against the regenerated schema:

value	before	after
eth0.10, bond0.4094, enp1s0f0.100, eth-0.1, eth_0.4094	accepted (no check)	accepted
eth0, vlan100, eth0.10.20, eth0.99999, .10, eth0.	accepted (no check)	rejected

make lint (includes verify-crd) passes with 0 issues; go build ./... and
go test ./pkg/util/... pass.

Compatibility

Existing ProviderNetwork resources that already hold a value the daemon
accepts stay valid — the pattern is strictly narrower than "any string" but
strictly wider than what the daemon has ever been able to program. A resource
holding an unparseable name (which never worked) will be rejected on its next
update.

🤖 Generated with Claude Code