`information_schema.columns` returns blank metadata instead of view columns

[fulghum]

Doltgres does not expose view output columns correctly through information_schema.columns. Each view is represented by a single fabricated row with an empty column name, ordinal position 0, and no type metadata.

Reproduction

CREATE TABLE view_metadata_probe (
    id integer,
    label varchar(20)
);

CREATE VIEW view_metadata_probe_v AS
SELECT id, label
FROM view_metadata_probe;

SELECT
    column_name,
    ordinal_position,
    data_type,
    udt_schema,
    udt_name
FROM information_schema.columns
WHERE table_schema = 'public'
  AND table_name = 'view_metadata_probe_v'
ORDER BY ordinal_position;

Doltgres result

The view is represented by one row resembling:

column_name | ordinal_position | data_type | udt_schema | udt_name
------------+------------------+-----------+------------+---------
            | 0                | NULL      | NULL       | NULL

PostgreSQL result

PostgreSQL 16 returns:

column_name | ordinal_position | data_type         | udt_schema | udt_name
------------+------------------+-------------------+------------+---------
id          | 1                | integer           | pg_catalog | int4
label       | 2                | character varying | pg_catalog | varchar

Impact

Schema-discovery tools and database clients cannot determine a view's columns or types through the standard information schema, even though the underlying view data is available.

Implementation context

getRowsFromViews in server/tables/information_schema/columns_table.go currently appends one literal placeholder row for each view. It does not analyze the view definition or iterate over its output schema.

The pg_attribute catalog already analyzes view queries and emits one entry per output column. The information-schema implementation should similarly derive the analyzed view schema and build a normal metadata row for each output column.

This was identified as a pre-existing issue while validating #3241.