test: exercise everyday SQL expressions in the sample and on PostgreSQL

[omer-cengel]

Summary

Extends the external Maven sample and the PostgreSQL integration tests so that the recently supported SQL idioms (named parameters, non-binding write values such as now(), cast-typed placeholders, grouped counts, upserts, and = ANY id lists) run end to end through generated code against a real database. No compiler, generator, or runtime behavior changes.

Changes

• Sample: a new V4 migration adds a nullable updated_at column to authors, so the shared AuthorsRow record gains LocalDateTime updatedAt.
• Sample: new queries for an optional name filter (:name::text IS NULL OR name = :name), a rename that sets updated_at = now(), a per-author book count with GROUP BY, an ON CONFLICT (id) DO UPDATE ... RETURNING * upsert, and an id = ANY(:ids) read.
• Sample application: a checked step for each new query, covering a null and a named filter, two ids and an empty id list, the grouped count, the rename's updated_at, and an upsert over an existing author.
• Release verification script: applies the new migration, checks that the five new repository methods and the updatedAt row component are generated, and keeps the existing generated-source and manifest checks.
• PostgreSQL integration tests: a read of unqualified columns over albums LEFT JOIN studios filtered by tags && $1::varchar[], and an insert that writes NOW() between its placeholders, binds an enum, an enum array, and a text[] value, and returns the generated id.

Scope and non-goals

• No change to SQL parsing, analysis, code generation, or the runtime.
• No new tables, constraints, or enums in the sample; the upsert targets the existing primary key and is exercised over an existing row.
• Constructs that remain unsupported (an unqualified column named like a date unit, a function as the FROM source, an unaliased COUNT(*)) are not newly tested.