Expose browser pool profile refresh state

[IlyaasK]

Summary

• expose refresh_on_profile_update as computed durable state on the kernel_browser_pool data source
• flatten the Kernel SDK response with the existing strict optional-boolean handling
• preserve known false, return null when omitted, and diagnose malformed API values
• assert the field for both ID and exact-name lookups in the existing acceptance fixture
• regenerate the data-source documentation

Why

Browser pools created outside Terraform should expose the same durable profile-refresh policy that the managed resource supports. This keeps read-only lookup behavior consistent with the Kernel API, SDK, and CLI.

Intentionally unsupported

This does not add runtime pool counters, leases, acquire/release/flush operations, force deletion, or any profile mutation behavior.

Verification

• gofmt -l cmd internal
• go test -short -timeout=2m ./...
• go vet ./...
• terraform fmt -check -recursive examples
• bash scripts/check-docs.sh
• bash scripts/check-markdown-links.sh
• focused tests cover true, known false, omitted, null, non-boolean, Terraform state shape, and both acceptance selectors

The guarded live acceptance matrix passed: https://github.com/kernel/terraform-provider-kernel/actions/runs/30667323827. All seven jobs passed, including browser-pool create/read/update/import/delete and browser-pool data-source lookup by ID and name.

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Note

Low Risk
Read-only data source and documentation changes only; no write paths or auth changes.

Overview
Adds computed read-only refresh_on_profile_update to the kernel_browser_pool data source so lookups return the same durable profile-refresh policy as the managed resource.

The value is flattened from browser_pool_config with the existing optional-boolean rules: null when the API omits the field, a known true/false when present, and diagnostics for null or non-boolean API values. Docs are regenerated; unit and acceptance tests cover schema, flatten behavior, and ID/name lookups.

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