[NPU] Support DeepSeek-V4 DSpark and refactor DSV4 cache management (#33676)

Co-authored-by: JiaruiChang5268 <jc5268@columbia.edu>
Co-authored-by: Kelon <kelonlu@163.com>
Co-authored-by: unknown <z8ruev42yk@gmail.com>
Co-authored-by: Talantan1102 <545811257@qq.com>
Co-authored-by: Talantan1102 <44429302+Talantan1102@users.noreply.github.com>

python/sglang/srt/server_args.py

@@ -893,6 +893,11 @@ class ServerArgs:
         Arg(help="The number of tokens in a page.", resolvable=True),
         NS("schedule"),
     ] = None
+    c128_page_size: A[
+        int,
+        "The physical page size of the NPU DSV4 C128 KV cache. Must be a positive multiple of 16.",
+        NS("schedule"),
+    ] = 16
     swa_full_tokens_ratio: A[
         float,
         Arg(