chore: support running multiple clients with same client id

[joker23]

This PR will implement support for running multiple LDClients with the same mobile key. We do this by adding an optional namespace option that will prefix the persistent storage path so there won't be any collisions.

This change is helpful in that we should provide a way to custom the namespaces for IPC connections.

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Note

Medium Risk
Changes how storage keys and IPC channel names are derived, which can affect cache isolation and renderer/main communication for existing multi-client apps. Most changes are additive and covered by updated unit/contract tests, but misconfigured namespaces could still cause collisions or disconnected renderer clients.

Overview
Adds an optional namespace option to allow multiple Electron SDK clients to run in the same process with the same credential without colliding on cache files or IPC handlers.

Introduces deriveNamespace() and uses the derived value to (a) hash storage filenames in ElectronPlatform and contract tests, and (b) scope IPC channel registration in ElectronClient plus renderer bridge initialization via ElectronRendererClient/createRendererClient.

Updates validation to accept namespace, exports deriveNamespace from the package, adjusts contract-test client creation to assign unique namespaces, and refactors/extends tests (shared mock logger helper, parameterized variation tests, new ElectronIPC unit tests, and migration docs explaining namespacing).

^{Reviewed by Cursor Bugbot for commit 451f17d. Bugbot is set up for automated code reviews on this repo. Configure here.}

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[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 25661 bytes
Compressed size limit: 29000
Uncompressed size: 126143 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 31736 bytes
Compressed size limit: 34000
Uncompressed size: 112937 bytes

[github-actions]

@launchdarkly/browser size report
This is the brotli compressed size of the ESM build.
Compressed size: 179348 bytes
Compressed size limit: 200000
Uncompressed size: 830127 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 37181 bytes
Compressed size limit: 38000
Uncompressed size: 204409 bytes

[joker23]

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[joker23]

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[joker23]

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[joker23]

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[joker23]

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[joker23]

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[joker23]

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

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[joker23]

This is the wrong implementation