chore(charts): add values.schema.json for Helm input validation

[ferponse]

Summary

The charts have no values.schema.json, so helm install does not validate user-provided values. Invalid or mistyped values (wrong types, unexpected keys) are silently ignored until the chart fails to render or the pod fails to start.

Closes #1255

Changes

• Adds values.schema.json to opensandbox-controller, opensandbox-server and opensandbox charts, generated from their respective values.yaml using the helm-schema plugin
• Adds .github/workflows/helm-schema.yml — triggers on PRs that touch values.yaml, regenerates the schema and auto-commits it

How it works

The JSON Schema is derived directly from values.yaml. Helm validates user-provided --set flags and -f values.yaml overrides against it at install/upgrade time. Examples of what gets caught:

# Type mismatch — caught at install time instead of runtime
helm install opensandbox-controller . --set controller.replicaCount=abc
# Error: values don't meet the specifications of the schema(s) in the following chart(s):
#   opensandbox-controller: controller.replicaCount: Invalid type. Expected: integer, given: string

# Unknown key typo — caught immediately
helm install opensandbox-controller . --set controller.replicaCont=2
# Error: additional properties 'replicaCont' not allowed

Verified locally

# All schemas are valid JSON
python3 -c "import json; json.load(open('values.schema.json'))"  # ✓ each chart

# helm lint passes with schemas present
helm lint kubernetes/charts/opensandbox-controller  # 1 chart(s) linted, 0 chart(s) failed
helm lint kubernetes/charts/opensandbox-server      # 1 chart(s) linted, 0 chart(s) failed

Notes

• No breaking change — users who don't pass invalid values are unaffected.
• Consistent with Helm best practices for production charts.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Allow global values in the umbrella schema

Helm validates the final .Values object against values.schema.json on install/upgrade/template (https://helm.sh/docs/topics/charts/#schema-files), so an all-in-one install with global: {} or the global.imagePullSecrets block advertised in kubernetes/charts/opensandbox/values.yaml now fails validation because this property only permits null. Please model global as an object with additional properties so standard parent-chart global values remain accepted.

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[chatgpt-codex-connector]

Allow fractional kube-client QPS values

The controller's --kube-client-qps flag is registered with flag.Float64Var (kubernetes/cmd/controller/main.go:197) and the template emits the raw value when positive, so a custom values file with controller.kubeClient.qps: 12.5 was valid before this schema. With Helm schema validation on the final values (https://helm.sh/docs/topics/charts/#schema-files), Helm now rejects that supported fractional QPS; use JSON Schema number for qps.

Useful? React with 👍 / 👎.

[ferponse]

Closing — auto-generated schemas produce incorrect types for edge cases (e.g. global: null instead of object, qps: integer instead of number). A hand-crafted schema would be more reliable but is out of scope for this PR. The chart-testing CI (#1260) already catches many issues without requiring a schema file.