feat: add boundary usage tracking database schema and tracker skeleton (#21670)

feat: add boundary usage telemetry database schema and RBAC

Adds the foundation for tracking boundary usage telemetry across Coder
replicas. This includes:

  - Database schema: `boundary_usage_stats` table with per-replica stats
    (unique workspaces, unique users, allowed/denied request counts)
  - Database queries: upsert stats, get aggregated summary, reset stats,
    delete by replica ID
  - RBAC: `boundary_usage` resource type with read/update/delete actions,
    accessible only via system `BoundaryUsageTracker` subject (not regular
    user roles)
  - Tracker skeleton + docs: stub implementation in `coderd/boundaryusage/`

The tracker accumulates stats in memory and periodically flushes to the
database. Stats are aggregated across replicas for telemetry reporting,
then reset when a new reporting period begins. The tracker implementation
and plumbing will be done in a subsequent commit/PR.

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

coderd/database/querier.go

@@ -88,6 +88,8 @@ type sqlcQuerier interface {
 	// be recreated.
 	DeleteAllWebpushSubscriptions(ctx context.Context) error
 	DeleteApplicationConnectAPIKeysByUserID(ctx context.Context, userID uuid.UUID) error
+	// Deletes boundary usage statistics for a specific replica.
+	DeleteBoundaryUsageStatsByReplicaID(ctx context.Context, replicaID uuid.UUID) error
 	DeleteCryptoKey(ctx context.Context, arg DeleteCryptoKeyParams) (CryptoKey, error)
 	DeleteCustomRole(ctx context.Context, arg DeleteCustomRoleParams) error
 	DeleteExpiredAPIKeys(ctx context.Context, arg DeleteExpiredAPIKeysParams) (int64, error)
@@ -194,6 +196,10 @@ type sqlcQuerier interface {
 	// This function returns roles for authorization purposes. Implied member roles
 	// are included.
 	GetAuthorizationUserRoles(ctx context.Context, userID uuid.UUID) (GetAuthorizationUserRolesRow, error)
+	// Aggregates boundary usage statistics across all replicas. Filters to only
+	// include data where window_start is within the given interval to exclude
+	// stale data.
+	GetBoundaryUsageSummary(ctx context.Context, maxStalenessMs int64) (GetBoundaryUsageSummaryRow, error)
 	GetConnectionLogsOffset(ctx context.Context, arg GetConnectionLogsOffsetParams) ([]GetConnectionLogsOffsetRow, error)
 	GetCoordinatorResumeTokenSigningKey(ctx context.Context) (string, error)
 	GetCryptoKeyByFeatureAndSequence(ctx context.Context, arg GetCryptoKeyByFeatureAndSequenceParams) (CryptoKey, error)
@@ -646,6 +652,9 @@ type sqlcQuerier interface {
 	RegisterWorkspaceProxy(ctx context.Context, arg RegisterWorkspaceProxyParams) (WorkspaceProxy, error)
 	RemoveUserFromAllGroups(ctx context.Context, userID uuid.UUID) error
 	RemoveUserFromGroups(ctx context.Context, arg RemoveUserFromGroupsParams) ([]uuid.UUID, error)
+	// Deletes all boundary usage statistics. Called after telemetry reports the
+	// aggregated stats. Each replica will insert a fresh row on its next flush.
+	ResetBoundaryUsageStats(ctx context.Context) error
 	RevokeDBCryptKey(ctx context.Context, activeKeyDigest string) error
 	// Note that this selects from the CTE, not the original table. The CTE is named
 	// the same as the original table to trick sqlc into reusing the existing struct
@@ -753,6 +762,10 @@ type sqlcQuerier interface {
 	UpsertAnnouncementBanners(ctx context.Context, value string) error
 	UpsertAppSecurityKey(ctx context.Context, value string) error
 	UpsertApplicationName(ctx context.Context, value string) error
+	// Upserts boundary usage statistics for a replica. All values are replaced with
+	// the current in-memory state. Returns true if this was an insert (new period),
+	// false if update.
+	UpsertBoundaryUsageStats(ctx context.Context, arg UpsertBoundaryUsageStatsParams) (bool, error)
 	UpsertConnectionLog(ctx context.Context, arg UpsertConnectionLogParams) (ConnectionLog, error)
 	UpsertCoordinatorResumeTokenSigningKey(ctx context.Context, value string) error
 	// The default proxy is implied and not actually stored in the database.