fix(pgwire): infer parameter types from SQL text on prepare

Server-inferred parameter types previously came only from DataFusion
plan analysis, which leaves positions like `LIMIT $1`/`OFFSET $1` and
explicit casts (`$1::BIGINT`) undescribed when the client sends no
declared oid. tokio-postgres then refuses to bind because the
parameter's wire type is unknown.

Add nodedb-sql::infer_placeholder_types to resolve a placeholder's
type directly from the surrounding SQL, and use it to fill any
parameter slot the client left undeclared, independent of whether the
plan-analysis pass succeeds.

Author: farhan-syah

nodedb-sql/src/lib.rs

@@ -22,6 +22,7 @@ pub mod functions;
 pub mod optimizer;
 pub mod params;
 pub mod parser;
+pub mod placeholder_types;
 pub mod planner;
 pub mod reserved;
 pub mod resolver;
@@ -39,6 +40,7 @@ pub use visitor::plan_visitor::args::*;
 pub use catalog::{SqlCatalog, SqlCatalogError};
 pub use error::{Result, SqlError};
 pub use params::ParamValue;
+pub use placeholder_types::infer_placeholder_types;
 pub use types::*;
 
 /// Parse a standalone SQL expression string into an `SqlExpr`.