feat(service,cron-job): add UI category to values.schema.json for schema-driven settings

[arunesh-j]

What

Adds a category key to each mutable top-level property in the service and cron-job chart schemas (values.schema.json).

Why

The ZopDay Helm-import Settings UI renders an editable form for imported helm.zop.dev services. We want that form grouped into tabs (Runtime / Compute / Environment / Advanced) without hardcoding field lists in the frontend. Instead, each chart property declares which tab it belongs to via category, helm-manager passes it through, and the UI is a generic transformer that groups by category.

Shared category vocabulary (same across all charts)

Category	service	cron-job
runtime	image, httpPort, metricsPort, ports, heartbeatURL, readinessProbe, livenessProbe	image, schedule, suspend, concurrencyPolicy, httpPort, metricsPort
compute	minCPU, minMemory, maxCPU, maxMemory, minReplicas, maxReplicas, hpa_enable, hpaCPU, hpaMemory	minCPU, minMemory, maxCPU, maxMemory
environment	envFrom, env, envList, appSecrets	envFrom, env, envList, appSecrets
advanced	nginx, command, alerts	command, alerts

The vocabulary is intentionally a fixed shared set — cron reuses the same four tabs, placing its schedule fields under runtime and simply omitting the scaling/ingress/probe fields it does not have. No chart-specific categories.

Non-mutable leaf properties (e.g. name) are left unannotated — helm-manager already drops them (it only emits fields with mutable: true or nested mutable properties), so no hidden marker is needed.

Safety

• Purely additive metadata. category is an unknown (and therefore ignored) JSON Schema keyword under draft-07, so helm lint passes and rendered manifests are byte-identical — zero functional change to deployed services.
• No version bump / no re-release. helm-manager fetches these schemas raw from the configured branch (raw.githubusercontent.com/zopdev/helm-charts/refs/heads/main/charts/<name>/values.schema.json), not from the packaged chart. Once merged to main the new category keys are live; Chart.yaml versions are unchanged.

Follow-ups (separate PRs, not in this repo)

• helm-manager — add Category to the FormField model and read props["category"] in createFormFieldFromProperties so the key reaches the UI (backward-compatible; charts without category omit it).
• frontend (zopday) — rebuild the Helm settings panel as a generic transformer that groups fields into tabs by category.