[ColtonWilley]

Adds an opt-in wolfprov-gcm-single-update context parameter for non-streaming AES-GCM builds such as FIPS v5. A caller that opts in passes the complete payload in one Update, setting the expected tag first when decrypting, so wolfProvider calls wolfCrypt one-shot instead of caching and replaying the payload. Existing callers are unchanged.

[Copilot]

🟡 Changes recommended

A rejected tag replacement can leave strict decryption using invalid tag bytes, and the interoperability tests may fail to obtain an independent OpenSSL reference or silently compare wolfCrypt against itself.

2 open issues

• Clear the tag-set flag when replacement validation fails · New
• Use an independent OpenSSL reference in replace-default deployments · New

What changed in this PR

Adds an opt-in single-update AES-GCM contract to avoid payload-prefix replay in nonstreaming wolfCrypt builds, while preserving the ordinary EVP path.

Changes:

• Adds capability discovery, authenticated single-update processing, and operation-state guards.
• Registers interoperability and ordinary split-update, reuse, and TLS regression tests.
• Documents the contract, test modes, and release-validation limits.

File	Description
test/​test_gcm_single_update.c	Adds interoperability vectors and contract-edge checks.
test/​test_gcm_ordinary_compat.c	Adds ordinary GCM reuse, split-update, and TLS regressions.
test/​include.am	Registers both test programs with make check.
src/​wp_aes_aead.c	Implements the optional nonstreaming GCM contract.
docs/​GCM_SINGLE_UPDATE.md	Documents usage, exclusions, and validation requirements.

_{Review effort: Balanced}