Add: [2B] declare HBG kernel resource capacity

[TaoZQY]

The HBG kernel path needs graph-dependent capacity before a context can allocate and freeze its execution slot. This revision rebases 2B on the current K1 lifecycle, the shared 2A contract, and the revised H1 Host-build boundary, then derives resource requirements directly from the completed GraphBuild.

What changed

• GraphResourceRequirements records H1's measured GM heap, compact runtime image, Graph Definition block, and the A5 scheduler upper bound. The query performs no device allocation, address binding, or H2D, and leaves its output unchanged on failure.
• RuntimeLayoutKey makes compatibility explicit across architecture, layout ABI, task capacity, and copied-arena boundaries. Equal byte totals cannot make incompatible A2/A3, A5, or task-window layouts share a slot.
• GraphCapacityPlan takes the maximum of each independent region, then rebuilds one aligned runtime-slot layout. It does not treat the largest prepacked total as sufficient and does not represent committed HBM.
• HBG-specific capacity and three-stream admission live under src/common/host_build_graph/; generic worker validation remains aligned with 2A. Only architecture-specific requirement generation stays in the A2/A3 and A5 runtime_maker.cpp files.
• The kernel contract declares per-run GM heap and runtime-slot content plus a dedicated non-hidden AICPU stream and hidden AICore stream. bind_kernel_streams requires those two streams and the borrowed caller stream to be non-null and pairwise distinct.
• Program mode continues through upload_for_program_mode. Kernel launch must consume a slot allocated and frozen during context prepare; this PR does not add launch-time allocation, blob transport, or restore fallback.

The resulting flow is: H1 Host build and validation → read-only requirements snapshot → combine all allowed workload snapshots into one capacity plan → a later context-prepare stage allocates/fixes the slot → each eager/captured invocation restores its own H2 blob into that slot and executes. ACLGraph replay reuses the captured blob and never repeats Host build.

Validation

• Repository pre-commit suite passed, including clang-format, clang-tidy, cpplint, markdownlint, ruff, and pyright.
• Runtime binaries rebuilt successfully for the available variants.
• C++ unit suite: 147/147 executables passed, including both HBG architecture suites and pipeline-contract loader coverage.
• Python K1/2A/H1 ABI and worker tests: 193 passed, 4 skipped.
• A2/A3 HBG simulation: 20 passed, 7 skipped.
• A5 HBG simulation: 21 passed.
• A2/A3 onboard HBG runtime: 46 passed, 1 skipped through task-submit on an architecture-verified device.
• A5 onboard was not run locally because the precheck identified this host as A2/A3; A5 behavior was covered by its C++ and simulator suites.

Dependency and review scope

Draft 2B. The PR still targets main and contains exactly one cumulative commit so it remains buildable while prerequisites are open. That commit carries the current K1 implementation from #2064, the current shared 2A contract from #2177, the revised H1 from #2171, and this HBG 2B layer. Their human authors are retained as co-authors.

Review the 2B-specific files first:

• src/common/host_build_graph/kernel_resource_plan.h
• src/common/host_build_graph/kernel_pipeline_contract.h
• simpler::hbg::get_graph_resource_requirements in both HBG runtime makers
• the kernel-requirement cases in tests/ut/cpp/common/test_hbg_host_graph_build.cpp

Actual stable-slot ownership, H2 blob serialization/transport, per-replay restore, and launch-time capacity enforcement remain in their later stages; 2B only supplies the complete declaration and admission inputs they must consume.

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