feat(analysis): analyze multi-row and SELECT-sourced inserts

[omer-cengel]

Summary

An INSERT can now write several VALUES rows or the rows of a SELECT, with every placeholder typed from the column it is written into. Bulk inserts such as INSERT INTO memberships (project_id, user_id) SELECT :projectId, unnest(:userIds::bigint[]) and multi-row inserts now compile without extra casts, where previously they were rejected.

Changes

• Several VALUES rows pair with the column list by position; a named placeholder repeated across rows is one parameter bound at each position. VALUES rows written inside parentheses at any depth are accepted.
• INSERT ... SELECT, parenthesized or not and with or without FROM, pairs its items with the column list by position. A placeholder item is typed and named by its target column, a cast item is named by its target column, direct columns resolve against the SELECT's own sources, and * / t.* count one item per source column.
• The insert's SELECT is analyzed like any other analyzed nested read: its join ON, WHERE, LIMIT, and OFFSET placeholders are typed by their clause rules, CTEs and subquery sources are read, and the insert target is not in scope.
• WITH clauses written after the column list are analyzed, on a SELECT and on a VALUES source, as well as before the INSERT.
• ON CONFLICT and RETURNING are accepted on every accepted row source.
• New diagnostics: INSERT column and value counts must match. for a row or a SELECT of the wrong width, and INSERT requires parenthesized VALUES rows or a SELECT. for VALUES ROW(...), a bare value element, and DEFAULT VALUES; a set operation as the row source keeps the set-operation diagnostic.
• Analyzer, generated-source compilation, and PostgreSQL integration tests cover the new shapes; the query documentation and the unsupported-query catalogue are updated.

Scope and non-goals

• UPDATE ... FROM and DELETE ... USING remain rejected.
• Set operations, recursive or data-modifying CTEs, LATERAL, JDBC batch execution, and COPY remain unsupported.
• RETURNING item rules, conflict-clause scopes, and the rules of other nested SELECTs are unchanged; a scalar subquery in an insert SELECT item is still typed only by casts.
• Executable SQL is passed through unchanged, and parameters still bind in textual order.