feat: add app status tracking to the backend (#17163)

This does ~95% of the backend work required to integrate the AI work.

Most left to integrate from the tasks branch is just frontend, which
will be a lot smaller I believe.

The real difference between this branch and that one is the abstraction
-- this now attaches statuses to apps, and returns the latest status
reported as part of a workspace.

This change enables us to have a similar UX to in the tasks branch, but
for agents other than Claude Code as well. Any app can report status
now.

coderd/database/dbmem/dbmem.go

@@ -259,6 +259,7 @@ type data struct {
 	workspaceAgentVolumeResourceMonitors []database.WorkspaceAgentVolumeResourceMonitor
 	workspaceAgentDevcontainers          []database.WorkspaceAgentDevcontainer
 	workspaceApps                        []database.WorkspaceApp
+	workspaceAppStatuses                 []database.WorkspaceAppStatus
 	workspaceAppAuditSessions            []database.WorkspaceAppAuditSession
 	workspaceAppStatsLastInsertID        int64
 	workspaceAppStats                    []database.WorkspaceAppStat
@@ -3697,6 +3698,34 @@ func (q *FakeQuerier) GetLatestCryptoKeyByFeature(_ context.Context, feature dat
 	return latestKey, nil
 }
 
+func (q *FakeQuerier) GetLatestWorkspaceAppStatusesByWorkspaceIDs(_ context.Context, ids []uuid.UUID) ([]database.WorkspaceAppStatus, error) {
+	q.mutex.RLock()
+	defer q.mutex.RUnlock()
+
+	// Map to track latest status per workspace ID
+	latestByWorkspace := make(map[uuid.UUID]database.WorkspaceAppStatus)
+
+	// Find latest status for each workspace ID
+	for _, appStatus := range q.workspaceAppStatuses {
+		if !slices.Contains(ids, appStatus.WorkspaceID) {
+			continue
+		}
+
+		current, exists := latestByWorkspace[appStatus.WorkspaceID]
+		if !exists || appStatus.CreatedAt.After(current.CreatedAt) {
+			latestByWorkspace[appStatus.WorkspaceID] = appStatus
+		}
+	}
+
+	// Convert map to slice
+	appStatuses := make([]database.WorkspaceAppStatus, 0, len(latestByWorkspace))
+	for _, status := range latestByWorkspace {
+		appStatuses = append(appStatuses, status)
+	}
+
+	return appStatuses, nil
+}
+
 func (q *FakeQuerier) GetLatestWorkspaceBuildByWorkspaceID(ctx context.Context, workspaceID uuid.UUID) (database.WorkspaceBuild, error) {
 	q.mutex.RLock()
 	defer q.mutex.RUnlock()
@@ -7488,6 +7517,21 @@ func (q *FakeQuerier) GetWorkspaceAppByAgentIDAndSlug(ctx context.Context, arg d
 	return q.getWorkspaceAppByAgentIDAndSlugNoLock(ctx, arg)
 }
 
+func (q *FakeQuerier) GetWorkspaceAppStatusesByAppIDs(_ context.Context, ids []uuid.UUID) ([]database.WorkspaceAppStatus, error) {
+	q.mutex.RLock()
+	defer q.mutex.RUnlock()
+
+	statuses := make([]database.WorkspaceAppStatus, 0)
+	for _, status := range q.workspaceAppStatuses {
+		for _, id := range ids {
+			if status.AppID == id {
+				statuses = append(statuses, status)
+			}
+		}
+	}
+	return statuses, nil
+}
+
 func (q *FakeQuerier) GetWorkspaceAppsByAgentID(_ context.Context, id uuid.UUID) ([]database.WorkspaceApp, error) {
 	q.mutex.RLock()
 	defer q.mutex.RUnlock()
@@ -9584,6 +9628,31 @@ InsertWorkspaceAppStatsLoop:
 	return nil
 }
 
+func (q *FakeQuerier) InsertWorkspaceAppStatus(_ context.Context, arg database.InsertWorkspaceAppStatusParams) (database.WorkspaceAppStatus, error) {
+	err := validateDatabaseType(arg)
+	if err != nil {
+		return database.WorkspaceAppStatus{}, err
+	}
+
+	q.mutex.Lock()
+	defer q.mutex.Unlock()
+
+	status := database.WorkspaceAppStatus{
+		ID:                 arg.ID,
+		CreatedAt:          arg.CreatedAt,
+		WorkspaceID:        arg.WorkspaceID,
+		AgentID:            arg.AgentID,
+		AppID:              arg.AppID,
+		NeedsUserAttention: arg.NeedsUserAttention,
+		State:              arg.State,
+		Message:            arg.Message,
+		Uri:                arg.Uri,
+		Icon:               arg.Icon,
+	}
+	q.workspaceAppStatuses = append(q.workspaceAppStatuses, status)
+	return status, nil
+}
+
 func (q *FakeQuerier) InsertWorkspaceBuild(_ context.Context, arg database.InsertWorkspaceBuildParams) error {
 	if err := validateDatabaseType(arg); err != nil {
 		return err