Expose target table and parameter clause context for plugin queries

[mrmeku]

Summary

• Adds update_table and delete_from_table fields to the Query message in protos/plugin/codegen.proto, matching the existing insert_into_table field
• Adds ParameterContext enum and context field to the Parameter message, surfacing which SQL clause each parameter belongs to (SET, WHERE, LIMIT, OFFSET, FUNCTION_ARG, etc.)
• Wires the compiler's already-resolved information through to the plugin interface — no new analysis logic needed

Closes #4317

Details

Target tables for UPDATE/DELETE

The compiler already resolves the target table for UPDATE and DELETE queries internally (it needs to for column type resolution in SET clauses and WHERE conditions). The first commit simply exposes that information to plugins via two new proto fields (update_table = 9 and delete_from_table = 10 on the Query message).

Parameter clause context

In internal/compiler/resolve.go, resolveCatalogRefs already switches on the parent AST node type to determine how to resolve each parameter. The second commit tags each Parameter with a ParameterContext enum value corresponding to that dispatch:

Parent type	Context
*ast.ResTarget	SET
*ast.A_Expr	WHERE
*ast.BetweenExpr	WHERE
*ast.In	WHERE
*ast.FuncCall	FUNCTION_ARG
*limitCount	LIMIT
*limitOffset	OFFSET
*ast.TypeCast, *ast.ParamRef, default	UNSPECIFIED

This lets plugins distinguish WHERE params from SET params without reparsing q.Text — which is especially valuable for audit-logging, row-level security, and change-data-capture plugins that need to reconstruct pre-mutation SELECT queries.

Both changes are additive to protobuf (new fields default to zero/UNSPECIFIED) and have no impact on existing Go codegen output.

Test plan

• Added UpdateAuthorBio UPDATE query to codegen_json endtoend test
• Verified update_table is populated for UPDATE queries
• Verified delete_from_table is populated for DELETE queries
• Verified insert_into_table unchanged for INSERT queries
• Verified all three target table fields are null for SELECT queries
• Verified parameter context values: SET for UPDATE SET params, WHERE for WHERE params
• Regenerated golden files for codegen_json and process_plugin_sqlc_gen_json
• Full go test ./... passes