Exclude current incomplete month from contributor_monthly

export_contributor_monthly was grouping by month with no upper bound,
so for a fresh fetch mid-month the rightmost cell carried partial data
and made recent activity look misleadingly low. Apply the same
HAVING month < current_month guard already used by
export_monthly_summary so both summaries treat "complete months" the
same way.

Surfaced while rendering the first quickwit heatmap on 2026-05-19 —
the 2026-05 column showed half-month counts next to full months.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: pront

src/commands/generate_summaries.rs

@@ -327,13 +327,15 @@ fn export_contributor_monthly(
     exclude_labels: Option<&[String]>,
 ) -> Result<()> {
     let (wc, params) = build_where(table, exclude_labels, &["user_login IS NOT NULL"]);
+    let current_month = Utc::now().format("%Y-%m").to_string();
     let query = format!(
         "SELECT substr({table}.created_at, 1, 7) AS month,
                 {table}.user_login AS user_login,
                 COUNT(*) AS count
          FROM {table}
          {wc}
          GROUP BY month, user_login
+         HAVING month < '{current_month}'
          ORDER BY month, count DESC"
     );
     write_query_to_csv(