sdk: expose the verifier authority in the Go/TypeScript/Python GlobalState deserializers

[elitegreg]

Part of RFC-27 (tracker: #4194). Depends on #4196.

GlobalState gains ip_verifier_authority_pk, so every SDK that deserializes it needs the new trailing field.

What

• sdk/serviceability Go, TypeScript, and Python GlobalState structs.
• Regenerate fixtures with make generate-fixtures and update the generator in sdk/serviceability/testdata/fixtures/generate-fixtures/.
• Keep older account data decoding: the field is appended, so a short buffer must yield the default pubkey rather than an error, matching how each SDK already handles feed_authority_pk.

Acceptance

• make sdk-test green across all three SDKs.
• A test per SDK decoding a pre-upgrade fixture and getting the default pubkey.