collab: Add GET /billing/usage endpoint (#28832)

This PR adds a `GET /billing/usage` endpoint for retrieving billing
usage to show on the `zed.dev/account` page.

Release Notes:

- N/A

crates/collab/src/llm/db/queries.rs

@@ -2,4 +2,5 @@ use super::*;
 
 pub mod billing_events;
 pub mod providers;
+pub mod subscription_usages;
 pub mod usages;

crates/collab/src/llm/db/queries/subscription_usages.rs

@@ -0,0 +1,22 @@
+use crate::db::UserId;
+
+use super::*;
+
+impl LlmDatabase {
+    pub async fn get_subscription_usage_for_period(
+        &self,
+        user_id: UserId,
+        period_start_at: DateTimeUtc,
+        period_end_at: DateTimeUtc,
+    ) -> Result<Option<subscription_usage::Model>> {
+        self.transaction(|tx| async move {
+            Ok(subscription_usage::Entity::find()
+                .filter(subscription_usage::Column::UserId.eq(user_id))
+                .filter(subscription_usage::Column::PeriodStartAt.eq(period_start_at))
+                .filter(subscription_usage::Column::PeriodEndAt.eq(period_end_at))
+                .one(&*tx)
+                .await?)
+        })
+        .await
+    }
+}

crates/collab/src/llm/db/tables.rs

@@ -2,5 +2,6 @@ pub mod billing_event;
 pub mod model;
 pub mod monthly_usage;
 pub mod provider;
+pub mod subscription_usage;
 pub mod usage;
 pub mod usage_measure;

crates/collab/src/llm/db/tables/subscription_usage.rs

@@ -0,0 +1,20 @@
+use crate::db::UserId;
+use sea_orm::entity::prelude::*;
+use time::PrimitiveDateTime;
+
+#[derive(Clone, Debug, PartialEq, DeriveEntityModel)]
+#[sea_orm(table_name = "subscription_usages")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub id: i32,
+    pub user_id: UserId,
+    pub period_start_at: PrimitiveDateTime,
+    pub period_end_at: PrimitiveDateTime,
+    pub model_requests: i32,
+    pub edit_predictions: i32,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {}
+
+impl ActiveModelBehavior for ActiveModel {}