chore: add copyright headers to packages test files

[karagozemin]

Add a per-file copyright header so ownership is visible at the file level (consistent with the root LICENSE).

Mechanical change — prepend this exact line as the first line of each file, nothing else:

// Copyright (c) 2026 Sub Rosa contributors

Add it to the following files:

• packages/sdk/src/asset-config.test.ts
• packages/sdk/src/client.test.ts
• packages/sdk/src/encoding.test.ts
• packages/sdk/src/encrypted-blob.test.ts
• packages/sdk/src/errors.test.ts
• packages/sdk/src/export-receipt.test.ts
• packages/sdk/src/ids.test.ts
• packages/sdk/src/mainnet-readiness.test.ts
• packages/sdk/src/preflight.test.ts
• packages/sdk/src/public-api-snapshot.test.ts
• packages/sdk/src/receipt.test.ts
• packages/sdk/src/redact.test.ts
• packages/sdk/src/status.test.ts
• packages/sdk/src/verify.test.ts
• packages/tlock/src/auditor-recovery-cli.test.ts
• packages/tlock/src/auditor.test.ts
• packages/tlock/src/bls.test.ts
• packages/tlock/src/commitment.test.ts
• packages/tlock/src/freshness.test.ts
• packages/tlock/src/quicknet.test.ts
• packages/tlock/src/seal.test.ts
• packages/round-bindings/src/event-snapshot.test.ts

[chainsmt]

I want to work on this issue.

[grantfox-oss]

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Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #217)
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