fix: resolve OUT-param varno by signature names for bare RETURN

[pyramation]

Summary

Fixes invalid SQL emitted for bare RETURN; in functions with OUT parameters. libpg-query@18 never serializes PLpgSQL_function.out_param_varno, so when the single OUT param is not datum 0 (i.e. IN params precede it), resolveOutParamVarno failed and the deparser rendered the compiler's retvarno as RETURN <out_param>; — which PostgreSQL rejects (RETURN cannot have a parameter in function with OUT parameters). This broke constructive-db's generate pipeline for functions like:

CREATE FUNCTION f(a text, b uuid, OUT result uuid) RETURNS uuid AS $$
BEGIN ... RETURN;  -- was deparsed as: RETURN result;
END$$ LANGUAGE plpgsql;

Changes:

• ReturnInfo gains outParamNames?: string[]; getReturnInfo (plpgsql-parser) populates it from FunctionParameter modes (OUT/INOUT/TABLE).
• resolveOutParamVarno first resolves by name: single OUT name → matching PLpgSQL_var datum index; multiple OUT names → the (unnamed row) datum whose fields match the names. Existing heuristics kept as fallback.
• plpgsql-deparser test harness now derives ReturnInfo from the fixture's CREATE FUNCTION signature (deriveReturnInfo), matching how plpgsql-parser's transform pipeline deparses.
• New fixtures: bare RETURN with single non-first OUT param and with multiple OUT params.

All suites green: plpgsql-deparser 106, plpgsql-parser 292, plpgsql-parse 57, parse 68. Verified against the 5 constructive-db functions that failed round-trip in its generate CI.

Link to Devin session: https://app.devin.ai/sessions/064ad193e1c040af8c145d55e07af9b8
Requested by: @pyramation

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[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	libpg-query@​18.1.2

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