Fix CLOB result set handling in MySQL Proxy

[terrymanu]

No description provided.

[terrymanu]

Result

Review Result: Mergeable

The CLOB/NCLOB metadata and row-encoding changes are internally consistent and preserve existing BLOB parameter safeguards.

Evidence

• Text and binary result paths now serialize Clob character streams using the negotiated charset, matching MySQL’s length-encoded string protocol. Current commit, MySQL text-row specification.
• CLOB metadata uses a non-binary charset, BLOB type/flag, and excludes binary/unsigned flags, consistent with MySQL column-definition semantics. Column definition, column flags.
• Prepared CLOB parameters retain a character-type decoding hint, avoiding the binary-data handling branch introduced for issue #39071.
• Focused verification passed: 51 tests across the changed MySQL protocol and Proxy frontend modules, exit code 0.

Coverage

• Reviewed head: e158c7561d5063f99136757607f993a3288a12e1.
• Base and merge-base: 47581cf0724557ec68a0e065054c865f437563fd.
• All 12 GitHub-listed files were accounted for and matched the local triple-dot scope: 6 production files and 6 tests.
• Reviewed clusters: JDBC-to-MySQL type mapping, text/binary CLOB row encoding, query-response metadata, and prepared-statement parameter/projection metadata.
• Completed root-cause, blast-radius/contracts, tests/runtime/operations, and final convergence passes.
• No unresolved evidence gaps or blocking findings.
• This is a code-scope correctness result only; CI was not reviewed.