Add m8id instance family (Granite Rapids + local NVMe)

m8id = m8i CPU + local NVMe. Mirrors m8i (GRANITE_RAPIDS_IPC, 3.9 GHz all-core)
and adds the local-NVMe ephemeral profile:
- instance_families.py: "m8id" entry with io_latency_curve "8th-gen-ssd".
- auto_shape.py: "8th-gen-ssd" latency curve from fio (4k randread, QD1, 60s),
  median across 20 m8id.4xlarge (confirmed by a separate 9-instance run):
  low/mid/high = p5/p50/p95 = 0.070/0.093/0.103 ms. Per-instance p50 is bimodal
  (~76us / ~93us clusters, ~35%/65% split), so the median is firmly ~93us.
  minimum_value 0.03 = realistic floor (clat-min ~0.5us is a cached-I/O
  artifact); maximum_value 1.2 = tail bound.
- auto_shape.py: aws_iops_per_gib "8id" = (303.5, 151.8). m8id's published
  instance-store IOPS match the m6id/m7gd per-GiB rate exactly (m8id.96xlarge =
  6,439,992 read / 3,220,008 write over 6x3800 GB = 22,800 GB).

Author: Jugad Khajuria

service_capacity_modeling/tools/auto_shape.py

@@ -23,6 +23,14 @@
 
 # Default latency curves from FIO testing per generation
 latency_curve_ms: Dict[str, FixedInterval] = {
+    "8th-gen-ssd": FixedInterval(
+        low=0.07,
+        mid=0.093,
+        high=0.103,
+        confidence=0.9,
+        minimum_value=0.03,
+        maximum_value=1.2,
+    ),
     "7th-gen-ephemeral": FixedInterval(
         low=0.071,
         mid=0.079,
@@ -88,6 +96,7 @@
     "6id": (303.5, 151.8),
     "6idn": (303.5, 151.8),
     "7gd": (303.5, 151.8),
+    "8id": (303.5, 151.8),
     # Compute has smaller IOPs
     "c5ad": (232.6, 101.5),
     "c5d": (430.1, 193.5),

service_capacity_modeling/tools/instance_families.py

@@ -218,6 +218,15 @@
         "cpu_turbo_single_ghz": 3.9,
         "cpu_turbo_all_ghz": 3.9,
     },
+    # m8id = m8i + local NVMe: same Granite Rapids CPU (GRANITE_RAPIDS_IPC, 3.9
+    # GHz), plus the 8th-gen-ssd ephemeral io-latency curve measured via fio.
+    "m8id": {
+        "iops_per_gib": None,
+        "io_latency_curve": "8th-gen-ssd",
+        "cpu_ipc_scale": GRANITE_RAPIDS_IPC,
+        "cpu_turbo_single_ghz": 3.9,
+        "cpu_turbo_all_ghz": 3.9,
+    },
     # "mac2-m2pro": {
     #     'iops_per_gib': None,
     #     'io_latency_curve': 'ssd',