feat: PostgREST-style document filtering and ordering

GET /collections/:id/documents accepts filter (field.op.value terms; eq neq
gt gte lt lte like in is; dotted paths index into document data) and order
(field.asc|desc). Whitelisted field/operator parsing with parameterized
values; plain lists keep the sqlc path. CLI gains `documents list
--collection --filter --order`; OpenAPI + generated client updated.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/repositories/core_repository.go

@@ -27,6 +27,12 @@ func (r *CoreRepository) Queries() *db.Queries {
 	return r.queries
 }
 
+// Pool exposes the pgx pool for dynamic queries sqlc can't express
+// (PostgREST-style document filtering builds its WHERE clause at runtime).
+func (r *CoreRepository) Pool() *pgxpool.Pool {
+	return r.pool
+}
+
 func (r *CoreRepository) WithTx(ctx context.Context, fn func(*db.Queries) error) error {
 	tx, err := r.pool.BeginTx(ctx, pgx.TxOptions{})
 	if err != nil {