feat(ui): add avg-by-hour panel to dashboard stats

Complements the existing avg-by-weekday chart with its orthogonal
partner: which hour of the day the user typically commits. The api
buckets events by EXTRACT(hour FROM occurred_at AT TIME ZONE $tz) so
the chart matches the clock the user sees rather than UTC; the UI
passes the browser's resolved IANA timezone. Renders as 24 mini-bars
below the weekday chart with labels every 4 hours and per-bar
tooltips showing the average events/day at that hour.

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

crates/moments-data/src/lib.rs

@@ -9,7 +9,7 @@ use async_trait::async_trait;
 use chrono::{DateTime, Utc};
 use moments_core::{EventReader, EventWriter, PollerState, PollerStateStore, StoreError};
 use chrono::NaiveDate;
-use moments_entities::{DailyCount, Event, EventQuery, LanguageDailyCount, ProjectSummary, RepoLanguage, Source, SourceSummary};
+use moments_entities::{DailyCount, Event, EventQuery, HourlyAvg, LanguageDailyCount, ProjectSummary, RepoLanguage, Source, SourceSummary};
 use sqlx::Row;
 use sqlx::postgres::{PgPool, PgPoolOptions};
 use std::str::FromStr;
@@ -291,6 +291,55 @@ impl EventReader for PgStore {
             .collect()
     }
 
+    async fn hourly_avgs(
+        &self,
+        from: NaiveDate,
+        to: NaiveDate,
+        tz: &str,
+        include_private: bool,
+    ) -> Result<Vec<HourlyAvg>, StoreError> {
+        // GREATEST guards against from > to (returns NaN-via-div-by-zero
+        // otherwise). EXTRACT(hour FROM tz-shifted timestamp) buckets each
+        // event into the user's local hour rather than UTC, so the chart
+        // matches the labels they'd see on a clock.
+        let rows = sqlx::query(
+            r#"
+            WITH params AS (
+                SELECT GREATEST(($2::date - $1::date + 1), 1)::float8 AS day_count
+            ),
+            bucketed AS (
+                SELECT EXTRACT(hour FROM (occurred_at AT TIME ZONE $3))::int AS hour
+                FROM events
+                WHERE occurred_at >= ($1::date::timestamp AT TIME ZONE 'UTC')
+                  AND occurred_at <  (($2::date + 1)::timestamp AT TIME ZONE 'UTC')
+                  AND ($4::bool OR public = true)
+            )
+            SELECT g.h::int AS hour,
+                   (COUNT(b.hour)::float8 / (SELECT day_count FROM params)) AS avg
+            FROM generate_series(0, 23) AS g(h)
+            LEFT JOIN bucketed b ON b.hour = g.h
+            GROUP BY g.h
+            ORDER BY g.h
+            "#,
+        )
+        .bind(from)
+        .bind(to)
+        .bind(tz)
+        .bind(include_private)
+        .fetch_all(&self.pool)
+        .await
+        .map_err(map_err)?;
+
+        rows.into_iter()
+            .map(|r| {
+                Ok(HourlyAvg {
+                    hour: r.try_get("hour").map_err(map_err)?,
+                    avg: r.try_get("avg").map_err(map_err)?,
+                })
+            })
+            .collect()
+    }
+
     async fn repo_languages(&self) -> Result<Vec<RepoLanguage>, StoreError> {
         let rows = sqlx::query(
             r#"