[ENH] Reduce complexity of run_flow_on_task func

[Omswastik-11]

Summary

This PR refactors run_flow_on_task, which had grown to ~160 lines with high cyclomatic complexity, by extracting small helper functions with clear, single responsibilities. The main function is now a readable orchestrator with clearly defined steps.

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Changes

Extracted helper functions

• _validate_flow_and_task_inputs
  Handles input validation and backward-compatible argument handling

• _sync_flow_with_server
  Synchronizes the flow with the server and checks for duplicate runs

• _prepare_run_environment
  Prepares environment information and run tags

• _create_run_from_results
  Builds the OpenMLRun object from execution results

Internal structure improvements

• Introduced a _RunResults NamedTuple to bundle execution outputs
  (data_content, trace, evaluations) and reduce long parameter lists

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Type Safety Improvements

• Replaced assert statements with explicit ValueError / TypeError exceptions
• Added type guards before accessing attributes that may be None
• Made boolean parameters keyword-only where appropriate

---

Fixes #1580

[codecov-commenter]

Codecov Report

❌ Patch coverage is 10.16949% with 53 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.62%. Comparing base (c5f68bf) to head (6771fb4).

Files with missing lines	Patch %	Lines
openml/runs/functions.py	10.16%	53 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1596      +/-   ##
==========================================
- Coverage   53.02%   52.62%   -0.41%     
==========================================
  Files          36       36              
  Lines        4326     4342      +16     
==========================================
- Hits         2294     2285       -9     
- Misses       2032     2057      +25     

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[geetu040]

Looks really nice, I have left a few comments with only minor changes requested.

[Omswastik-11]

added cast(int , task_id) because of mypy pre-commit error .

[geetu040]

Nicely refactored, LGTM.

CC: @fkiraly, @SimonBlanke for review/merge.