fix(constraint): preserve AddData integer precision during JSON round-trip

[sozercan]

Motivation

• Client.AddData previously round-tripped referential/inventory data using encoding/json Marshal/Unmarshal, which decodes numbers to float64 and can lose precision for integers > 2^53.
• The local Rego driver disables in‑memory RoundTripOnWrite, so callers must preserve numeric precision when preparing data for driver storage to avoid policy-evaluation corruption.

Description

• Replaced the encoding/json Marshal/Unmarshal round-trip in Client.AddData with OPA's util.RoundTrip to preserve numeric precision by decoding numbers as json.Number (UseNumber).
• Removed the unused encoding/json import and added github.com/open-policy-agent/opa/v1/util to the imports in constraint/pkg/client/client.go.
• The change is minimal and localized to the data round-trip step so untyped JSON coercion for drivers is preserved while avoiding float64 precision loss; the inmem.OptRoundTripOnWrite(false) performance behavior is unchanged.

Testing

• Ran go test ./pkg/client -run TestClient_AddData -count=1 and the test passed (ok github.com/open-policy-agent/frameworks/constraint/pkg/client).
• Built and ran the client package tests locally with go test ./pkg/client and observed successful completion for the modified unit test(s).

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Codex Task

[Copilot]

Pull request overview

This PR updates Client.AddData to avoid integer precision loss when round-tripping referential/inventory data through JSON before writing to driver storage.

Changes:

• Replaced encoding/json marshal/unmarshal round-trip with opa/util.RoundTrip (UseNumber) to preserve numeric precision.
• Removed the unused encoding/json import and added github.com/open-policy-agent/opa/v1/util.

Show a summary per file

File	Description
constraint/pkg/client/client.go	Uses OPA’s JSON round-trip helper to prevent large integer coercion to float64 during AddData processing.

Copilot's findings

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• Files reviewed: 1/1 changed files
• Comments generated: 1

[Copilot]

The AddData round-trip behavior change is intended to preserve integer precision (>2^53) but there is no unit test here exercising a payload with a large integer and asserting it is not coerced to float64. Adding a focused test case (e.g., data containing an int64 just above 2^53) would prevent regressions and validate the motivation for using util.RoundTrip/UseNumber.