Model heat-aware admission and SSD write pressure offline

.github/workflows/ci.yml

@@ -37,6 +37,7 @@ jobs:
       - run: python -m pip install --upgrade pip
       - run: python -m pip install -e ".[test]"
       - run: python -m pytest sparkcache -q
+      - run: python -m pytest research -q
       - run: python -m pytest deploy -q
 
   package:

research/__init__.py

@@ -0,0 +1 @@
+"""Offline research prototypes that are excluded from SparkCache packages."""

research/heat_ssd_control/__init__.py

@@ -0,0 +1,11 @@
+"""SparkCache heat-aware admission and SSD-control prototype.
+
+**Research-only. Offline and excluded from SparkCache packages.**
+
+No production SparkCache module imports this package, and this module imports
+nothing from SparkCache production code. It models heat counters,
+shadow admission, and write-budget accounting entirely in process memory with
+no I/O and no serving dependency. Constructing any object here has no effect
+on storage or serving behavior. GPU-free behavior and import-isolation
+regressions live in ``research/heat_ssd_control/test_prototype.py``.
+"""