feat: add prebuilds metrics collector (#17547)

Closes https://github.com/coder/internal/issues/509

---------

Signed-off-by: Danny Kopping <dannykopping@gmail.com>

coderd/prebuilds/api.go

@@ -5,6 +5,8 @@ import (
 
 	"github.com/google/uuid"
 	"golang.org/x/xerrors"
+
+	"github.com/coder/coder/v2/coderd/database"
 )
 
 var ErrNoClaimablePrebuiltWorkspaces = xerrors.New("no claimable prebuilt workspaces found")
@@ -25,12 +27,23 @@ type ReconciliationOrchestrator interface {
 }
 
 type Reconciler interface {
+	StateSnapshotter
+
 	// ReconcileAll orchestrates the reconciliation of all prebuilds across all templates.
 	// It takes a global snapshot of the system state and then reconciles each preset
 	// in parallel, creating or deleting prebuilds as needed to reach their desired states.
 	ReconcileAll(ctx context.Context) error
 }
 
+// StateSnapshotter defines the operations necessary to capture workspace prebuilds state.
+type StateSnapshotter interface {
+	// SnapshotState captures the current state of all prebuilds across templates.
+	// It creates a global database snapshot that can be viewed as a collection of PresetSnapshots,
+	// each representing the state of prebuilds for a specific preset.
+	// MUST be called inside a repeatable-read transaction.
+	SnapshotState(ctx context.Context, store database.Store) (*GlobalSnapshot, error)
+}
+
 type Claimer interface {
 	Claim(ctx context.Context, userID uuid.UUID, name string, presetID uuid.UUID) (*uuid.UUID, error)
 	Initiator() uuid.UUID