Refactor: decompose ConfigPanel.vue (~1700 lines) into per-node-type field subcomponents

[pparage]

Context

src/components/ConfigPanel.vue is ~1719 lines: one modal with 13+ inline v-if="node.type === '...'" field bodies (vm, lxc, docker, network, router, switch, firewall, loadbalancer, dns, dhcp, group, simulated-internet, edge-firewall, vuln-target, shared-service), plus shared chrome (header/footer/status/lifecycle). It does too much for one file — harder to reason about, test, and iterate on.

Proposal

Extract each node-type field body into a focused subcomponent under src/components/ConfigPanel/ (e.g. VmFields.vue, FirewallFields.vue, SwitchFields.vue, …), leaving ConfigPanel.vue as the modal shell + header/footer + dispatch (~300-400 lines). Shared bits (common name/tags/role, deployed-VM status card) can become their own units too.

Notes / risks

• Behavior-preserving refactor only — keep all v-model/config bindings, emits (close/update/delete/update:attachments), handleVmAction/handleSave/handleDelete, defineExpose({ openApplyDialog }).
• Keep src/__tests__/configPanelVmAction.test.js green; the stub list there will need updating if components are extracted.
• Adds per-type unit-test seams as a bonus.

Deferred from the 2026-06-09 ConfigPanel UI/UX polish (that pass deliberately did chrome only, not structural decomposition).