fix: weight language graph by repo language proportions

Each commit was counted once per language in the repo regardless of
that language's share, so Shell (present in many repos as small
deploy scripts) appeared larger than Rust. Now weights each commit
by the language's byte proportion in the repo (e.g. a commit to a
95% Rust / 5% Shell repo contributes 0.95 to Rust, 0.05 to Shell).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/moments-data/src/lib.rs

@@ -229,14 +229,17 @@ impl EventReader for PgStore {
     async fn language_daily_counts(&self, from: NaiveDate, to: NaiveDate) -> Result<Vec<LanguageDailyCount>, StoreError> {
         let rows = sqlx::query(
             r#"
+            SELECT date, language, color,
+                   ROUND(SUM(weight))::bigint AS commits
+            FROM (
                 SELECT d::date AS date,
                        rl.language,
-                   COALESCE(MAX(rl.color),
+                       COALESCE(rl.color,
                            (SELECT color FROM repo_languages
                             WHERE language = rl.language AND color IS NOT NULL
                             LIMIT 1)
                        ) AS color,
-                   COUNT(e.id)::bigint AS commits
+                       rl.bytes::float / NULLIF(rt.total, 0) AS weight
                 FROM generate_series($1::date, $2::date, '1 day') d
                 JOIN events e
                   ON e.occurred_at >= (d::date || 'T00:00:00Z')::timestamptz
@@ -257,8 +260,15 @@ impl EventReader for PgStore {
                       )
                       ELSE NULL
                   END
-            GROUP BY d::date, rl.language
-            ORDER BY d::date, commits DESC
+                JOIN LATERAL (
+                    SELECT SUM(bytes)::float AS total
+                    FROM repo_languages r2
+                    WHERE r2.source = rl.source AND r2.repo = rl.repo
+                ) rt ON true
+            ) weighted
+            GROUP BY date, language, color
+            HAVING ROUND(SUM(weight)) > 0
+            ORDER BY date, commits DESC
             "#,
         )
         .bind(from)