feat: add DGR-001 performance contract

.scratch/distributed-gguf-runtime/evidence/DGR-001/performance-contract.json

@@ -0,0 +1,51 @@
+{
+  "benchmark_lanes": [
+    {
+      "concurrency_levels": [
+        1,
+        4
+      ],
+      "id": "transformers-safetensors",
+      "recipe": "current safetensors recipe",
+      "runtime": "transformers"
+    },
+    {
+      "concurrency_levels": [
+        1,
+        4
+      ],
+      "id": "llama-cpp-gguf",
+      "recipe": "whole-model GGUF recipe",
+      "runtime": "llama.cpp"
+    }
+  ],
+  "metrics": [
+    "ttft_ms",
+    "prefill_tok_per_sec",
+    "decode_tok_per_sec",
+    "p50_latency_ms",
+    "p95_latency_ms",
+    "aggregate_throughput_tok_per_sec",
+    "rss_bytes",
+    "vram_bytes",
+    "artifact_bytes",
+    "failure_count",
+    "output_drift"
+  ],
+  "model_target": {
+    "architecture": "deepseek2",
+    "gguf_quant": "Q2_K",
+    "gguf_repo": "second-state/DeepSeek-V2-Lite-Chat-GGUF",
+    "gguf_size_gb": 6.43,
+    "name": "DeepSeek-V2-Lite-Chat",
+    "rationale": "Smallest DeepSeek-family benchmark anchor that still points toward DeepSeek-V4-Flash; keeps the runtime on the DeepSeek2 path instead of falling back to a tiny but architecture-mismatched smoke model.",
+    "safetensors_repo": "deepseek-ai/DeepSeek-V2-Lite-Chat"
+  },
+  "notes": [
+    "Real model execution stays opt-in and must keep model artifacts on the mounted drive.",
+    "Use the tiny fallback only for loader plumbing smoke tests; it does not replace the architecture-aligned baseline."
+  ],
+  "schema_version": 1,
+  "stop_condition": "Stop if GGUF does not provide a meaningful speed or fit benefit over the safetensors baseline for the chosen DeepSeek-family model target.",
+  "story_id": "DGR-001"
+}