refactor(queries): replace hardcoded event types with constants

Replaced hardcoded `event_type` values with named constants from
`EVENT_TYPE`, as in #3614. Added the `BOUNCE_THRESHOLD` constant and
documented it in `docker-compose.yml`.

src/queries/sql/sessions/getWebsiteSessions.ts

@@ -50,8 +50,8 @@ async function relationalQuery(websiteId: string, filters: QueryFilters) {
       min(website_event.created_at) as "firstAt",
       max(website_event.created_at) as "lastAt",
       count(distinct website_event.visit_id) as "visits",
-      sum(case when website_event.event_type = 1 then 1 else 0 end) as "views",
-      sum(case when website_event.event_type = 2 then 1 else 0 end) as "events",
+      sum(case when website_event.event_type = ${EVENT_TYPE.pageView} then 1 else 0 end) as "views",
+      sum(case when website_event.event_type = ${EVENT_TYPE.customEvent} then 1 else 0 end) as "events",
       max(website_event.created_at) as "createdAt"
     from website_event 
     ${cohortQuery}
@@ -125,8 +125,8 @@ async function clickhouseQuery(websiteId: string, filters: QueryFilters) {
       ${getDateStringSQL('min(created_at)')} as firstAt,
       ${getDateStringSQL('max(created_at)')} as lastAt,
       uniq(visit_id) as visits,
-      sumIf(1, event_type = 1) as views,
-      sumIf(1, event_type = 2) as events,
+      sumIf(1, event_type = ${EVENT_TYPE.pageView}) as views,
+      sumIf(1, event_type = ${EVENT_TYPE.customEvent}) as events,
       max(created_at) as createdAt
     from website_event
     ${cohortQuery}
@@ -155,7 +155,7 @@ async function clickhouseQuery(websiteId: string, filters: QueryFilters) {
       ${getDateStringSQL('min(min_time)')} as firstAt,
       ${getDateStringSQL('max(max_time)')} as lastAt,
       uniq(visit_id) as visits,
-      sumIf(views, event_type = 1) as views,
+      sumIf(views, event_type = ${EVENT_TYPE.pageView}) as views,
       sum(length(event_name)) as events,
       max(max_time) as createdAt
     from website_event_stats_hourly as website_event