kernels: name compilation entries by storage route (uniform.cu, blocked.cu)

kernel_v2.cu -> uniform.cu (whole-domain NX/NY, Simulation) and
blocks.cu -> blocked.cu (one block window, every blocked level), with
InitTubeFlow_v2 -> InitTubeFlow. All live callers, include comments,
CONFIG.md, lifecycle doc and current-tree tests move together; no alias.
refinement.cu keeps its name until the dense-route decision.
Historical-revision tooling that names the old files (LES source pins,
timing/J campaign runners, TG run_case, supported_settings citations at
888c8038, development notes) is unchanged on purpose.
No arithmetic change; the PTX symbol InitTubeFlow_v2 is renamed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/validation/multigrid/test_channel_root_gpu.py

@@ -27,7 +27,7 @@ def state(ny, nx):
 
 def compile_module(cfg, context, source):
     cfg.validate()
-    build = compiler.generate_config(cfg, block_root_bc=2 if source == "blocks.cu" else 0)
+    build = compiler.generate_config(cfg, block_root_bc=2 if source == "blocked.cu" else 0)
     try:
         module = compiler.load_module(compiler.compile_kernel(context.sm_arch, source=source, build_dir=build))
     finally:
@@ -46,7 +46,7 @@ def run_root(cfg, context, initial, block=None, steps=8):
     try:
         layout = None if block is None else BlockLayout2D.build(cfg.ny, cfg.nx, *block)
         local = cfg if layout is None else replace(cfg, nx=layout.local_shape[1], ny=layout.local_shape[0])
-        module = compile_module(local, context, "kernel_v2.cu" if layout is None else "blocks.cu")
+        module = compile_module(local, context, "uniform.cu" if layout is None else "blocked.cu")
         data = initial if layout is None else layout.to_blocked(initial)
         current, spare = upload(data), upload(np.full_like(data, np.nan))
         tpb = cfg.threads_per_block