Phase 68: PGO training set diversification (seed/WS expansion)

Changes:
- scripts/box/pgo_fast_profile_config.sh: Expanded WS patterns (3→5) and seeds (1→3)
  for reduced overfitting and better production workload representativeness
- PERFORMANCE_TARGETS_SCORECARD.md: Phase 68 baseline promoted (61.614M = 50.93%)
- CURRENT_TASK.md: Phase 68 marked complete, Phase 67a (layout tax forensics) set Active

Results:
- 10-run verification: +1.19% vs Phase 66 baseline (GO, >+1.0% threshold)
- M1 milestone: 50.93% of mimalloc (target 50%, exceeded by +0.93pp)
- Stability: 10-run mean/median with <2.1% CV

🤖 Generated with Claude Code

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

scripts/box/pgo_tiny_profile_box.sh

@@ -10,7 +10,8 @@
 set -e  # Fail fast on errors
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
-source "${SCRIPT_DIR}/pgo_tiny_profile_config.sh"
+PGO_CONFIG_BASENAME="${PGO_CONFIG:-pgo_tiny_profile_config.sh}"
+source "${SCRIPT_DIR}/${PGO_CONFIG_BASENAME}"
 
 echo "========================================="
 echo "Box: PGO Profile Collection (Tiny Front)"
@@ -18,6 +19,7 @@ echo "========================================="
 echo "Date: $(date)"
 echo "Workloads: $PGO_WORKLOAD_COUNT"
 echo "Binaries: $PGO_BINARY_COUNT"
+echo "Config: $PGO_CONFIG_BASENAME"
 echo ""
 
 # Validate binaries exist and are executable
@@ -58,7 +60,7 @@ for workload in "${PGO_WORKLOADS[@]}"; do
     echo "-------------------------------------------"
 
     # Execute with timeout (30s per workload)
-    if timeout 30 $workload; then
+    if timeout 30 bash -lc "$workload"; then
         echo "  ✓ Success"
     else
         EXIT_CODE=$?