test: add unit tests for grok_python helpers

[nuthalapativarun]

Summary

• Add 24 unit tests for grok_python helper functions: parse_sentences, is_punctuation (from helper.py) and ThinkParser (from openai.py)
• Add conftest.py that stubs ten_runtime, ten_ai_base, openai, PIL, and requests so pure-Python tests run without a full TEN runtime installation
• No changes to production code

What is tested

is_punctuation (3 tests)

• English punctuation (, . ? !) correctly identified
• Chinese punctuation (，。？！) correctly identified
• Letters, digits, spaces are not punctuation

parse_sentences (12 tests)

• Single complete sentence extracted correctly
• Multiple sentences split at punctuation boundaries
• Incomplete trailing text held in remain fragment
• Prefix fragment prepended to next chunk content
• Chinese punctuation splits
• Mixed punctuation types
• Punctuation-only tokens not emitted (no alphanumeric content)
• Empty inputs handled safely

ThinkParser (9 tests)

• Initial state is NORMAL
• <think> token transitions state to THINK, returns True
• </think> token transitions back to NORMAL, returns True
• Plain text in NORMAL state returns False, no state change
• Content in THINK state accumulated in think_content
• Content in NORMAL state does not accumulate
• process_by_reasoning_content() opens THINK on non-empty string
• process_by_reasoning_content("") closes THINK block
• Empty string in NORMAL state returns False

Test plan

• python3 -m pytest ai_agents/agents/ten_packages/extension/grok_python/tests/ -v — 24/24 passed
• task format — clean (no production code changes)