perf: replace paged KV cache with contiguous ContiguousCache, decode all groups

- Add KVCache/CacheView abstract base classes in cache.py
- Add ContiguousCache (contiguous per-slot buffer, default) alongside PageCache (paged, renamed from old KVCache)
- Merge make_table_tensor + bind into bind_tasks on KVCache interface
- Remove task_cached/task_record_hashes from base class (PageCache-only)
- Scheduler: decode all position groups instead of just the largest (eliminates 63% group skip rate)
- Scheduler: accept optional cache param for swapping implementations
- Model layer type hints use CacheView base class
- Batch 1-32: 1-7% speedup from eliminating Storage.gather overhead
- All 183 inference tests pass

astrai/inference/__init__.py

@@ -30,10 +30,14 @@ from astrai.inference.api.openai import OpenAIResponseBuilder
 from astrai.inference.core import (
     STOP,
     Allocator,
+    CacheView,
+    ContiguousCache,
+    ContiguousCacheView,
     Executor,
     InferenceScheduler,
     KVCache,
-    KvcacheView,
+    PageCache,
+    PageCacheView,
     PagePool,
     PrefixCache,
     Storage,
@@ -63,8 +67,12 @@ __all__ = [
     "TaskManager",
     "TaskStatus",
     "Allocator",
+    "CacheView",
     "KVCache",
-    "KvcacheView",
+    "ContiguousCache",
+    "ContiguousCacheView",
+    "PageCache",
+    "PageCacheView",
     "PagePool",
     "PrefixCache",
     "Storage",