Write ONE short caption (≤2 sentences, plain English, no markdown) that
summarises the answer to the user's question, given the SQL that was run
and the resulting data shape. Mention specific values when one or two rows
contain the punchline; otherwise describe the shape of the answer.

# Question
{question}

# SQL executed
{sql}

# Result shape
- columns: {columns}
- row count: {row_count}
- preview (up to 5 rows): {preview}

# Constraints
- ≤2 sentences.
- No "based on the data" filler.
- If the result is empty, say so plainly.
- Do NOT echo the full SQL.

Output only the caption text, nothing else.