fix(ascend): use CommInitAll for single-node TP

[baominghelly]

Summary

• Use infinicclCommInitAll for Ascend single-node tensor-parallel communicator initialization.
• Keep the existing GetUniqueId / CommInitRank path for platforms that support rank-based initialization.
• Add a static contract test requiring Ascend single-node TP to use CommInitAll rather than CommInitRank.

Motivation

The current Ascend HCCL backend in InfiniCCL supports CommInitAll, AllReduce, and CommDestroy, but does not support GetUniqueId or CommInitRank. As a result, Ascend TP initialization fails with:

RuntimeError: InfiniCCL operation `infinicclGetUniqueId` failed with result 8

This change aligns InfiniLM with the current Ascend InfiniCCL contract. It depends on the Ascend HCCL backend changes tracked in InfiniCCL PR #73.

Type of Change

• fix — bug fix

Test Results of Involved Models on Supported Platforms

Tested on Ascend 910C with the modern InfiniRT / InfiniOps / InfiniCCL stack and InfiniLM refactor/adopt-modern-infini-stack at 3faa1db.

Verified communicator initialization:

• TP2: established successfully.
• TP4: established successfully.
• TP8: established successfully.

Representative inference results after the fix:

• FM9G_70B, flash/paged attention, TP8: command completed and generated coherent Chinese output.
• Qwen3-32B, flash/paged attention, TP4: generated a valid thinking block and final answer.
• Llama-3.3-70B-Instruct, flash/paged attention, TP8: generated coherent Chinese output.
• Baichuan2-7B-Chat, flash/paged attention, TP2: generated a coherent factual response.

Static test:

python test/static/test_infinicore_runtime_contracts.py \
  InfiniCoreRuntimeContractsTest.test_ascend_single_node_tp_uses_comm_init_all

Ran 1 test in ... OK

Benchmark / Performance Impact

N/A. This is a correctness fix required before Ascend TP inference can initialize.

Notes for Reviewers

• This PR intentionally only changes communicator initialization and its contract test.
• Dense-prefill correctness changes and Ascend graph capture diagnostics are kept as separate follow-ups.
• Cross-node pipeline-parallel initialization still uses the rank-based path through initializeCommunicators; this PR only changes the intra-node TP path.

CI / ChatOps

CI needs to be triggered manually from the Actions tab, or by a maintainer with /retest or /test.

Checklist

Title, Branch, and Commits

• PR title follows Conventional Commits.
• Branch name follows <type>/xxx-yyyy-zzzz.
• Commit message follows Conventional Commits.
• Small PR is a single squashable commit.
• No stray merge commits from main.
• No fixup! / squash! / wip commits remain.
• Existing PR/branch/commit that followed the legacy issue format.

Scope and Design

• Changes are minimal and scoped to Ascend TP initialization.
• No dead code, debug prints, or unrelated formatting churn.
• No public API changes.

General Code Hygiene

• Comments are limited to the non-obvious platform contract.
• Files end with a newline.
• No trailing whitespace or BOMs.
• Comments and identifiers use English and backticks where appropriate.

C++ Specific

• Code follows the existing style.
• No new raw new / delete.
• Changed files are formatted according to the existing source style.
• No changes to csrc/models/llama_legacy/.

Python Specific

• Test code follows the existing static contract-test style.

Testing

• Affected platform tested on Ascend 910C.
• Passed representative single-request and offline inference checks for TP2/TP4/TP8.
• Sanity and service suites not run because this draft is narrowly scoped to communicator initialization.

Build, CI, and Tooling

• Incremental release build and _infinilm install passed on Ascend.
• CI still needs to be triggered manually.

Documentation

• No developer workflow or public behavior documentation change is needed.

Security and Safety

• No secrets, internal URLs, customer data, or personal hardware identifiers are committed.
• No third-party code was introduced.
• No unsafe pointer arithmetic or missing bounds checks were introduced.