Refine pruner checks and docs

Co-authored-by: julienrbrt <29894366+julienrbrt@users.noreply.github.com>

Author: Copilot

block/internal/pruner/pruner.go

@@ -125,10 +125,7 @@ func (p *Pruner) pruneOnce(ctx context.Context) error {
 	}
 
 	target := height - p.retention
-	if target < p.lastPruned {
-		return nil
-	}
-	if target == p.lastPruned {
+	if target <= p.lastPruned {
 		return nil
 	}
 

execution/evm/execution.go

@@ -268,6 +268,7 @@ func NewEngineExecutionClient(
 
 // PruneExecMeta removes execution metadata at the given height.
 // It is used by the block pruner to delete historical exec meta entries.
+// Returns nil if no store is configured.
 func (c *EngineClient) PruneExecMeta(ctx context.Context, height uint64) error {
 	if c.store == nil {
 		return nil