Initial commit: E4B-MarkBase model integration with passing tests

- E4B-MarkBase model (42 layers, 4.4GB) loaded successfully
- All Phase 1-6 tests passed (model loading, forward pass, vision/audio towers, token generation, performance)
- All stress tests passed (5/5 in 127.6s)
  - Concurrent inference
  - Memory stress (67.5 tok/s, 0 NaN)
  - Continuous generation
  - Batch processing
  - Long-running stability
- Swift Metal inference engine with multimodal support

Sources/test26b_std_main.swift

@@ -0,0 +1,35 @@
+import Foundation
+import MarkBase
+
+// Test harness for 26B-standard model
+let modelDir = "/Users/accusys/MarkBaseEngine/models/gemma-4-26b-standard"
+
+guard FileManager.default.fileExists(atPath: modelDir + "/config.json") else {
+    print("Model not found")
+    exit(1)
+}
+
+print("Loading engine...")
+let engine = try MarkBaseEngine(autoCompile: true)
+print("✓ Engine created")
+
+print("\nLoading 26B Standard model (~15 GB, may take 2-3 minutes)...")
+let start = Date()
+let model = try E4BModel(modelDir: modelDir, engine: engine, maxContextLength: 128)
+let loadTime = Date().timeIntervalSince(start)
+
+print("✓ Model loaded in \(String(format: "%.1f", loadTime))s")
+print("  Layers: \(model.numHiddenLayers)")
+print("  Hidden: \(model.hiddenSize)")
+print("  Vocab: \(model.vocabSize)")
+
+// Forward pass
+print("\n=== Forward pass test ===")
+let logits = try model.forward(tokenId: 2, position: 0)
+print("✓ Forward pass complete: \(logits.count) logits")
+print("  Max logit: \(logits.max() ?? -999)")
+let sorted = logits.enumerated().sorted { $0.element > $1.element }
+let top5 = sorted.prefix(5)
+print("  Top 5: \(top5.map { "\($0.offset):\(String(format: "%.2f", $0.element))" }.joined(separator: ", "))")
+
+print("\n✅ 26B Standard test complete!")