[docs] Documentation consistency fixes across doc/ folder

[github-actions]

Summary

This PR fixes documentation inconsistencies found across the doc/ folder by auditing every markdown file against the current source code and repository structure.

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Changes Made

1. doc/dev/release.md — Remove non-existent build_package.py script

Issue: "To build a package manually" instruction referenced python .\build_package.py azure-mgmt-myservice, but this script does not exist at the repo root.
Fix: Replaced with python -m build sdk/(service-dir)/azure-mgmt-myservice (using the standard build package, consistent with modern Python packaging practice). Also fixed the prose — the original sentence was incomplete: "This will a sdist and a wheel file."

2. doc/dev/engineering_assumptions.md — Update CI Python wheel-build version

Issue: States wheels are generated "by a CI step running Python 3.6." CI has used Python 3.9+ for years; Python 3.6 reached EOL in December 2021.
Fix: Changed Python 3.6 → Python 3.9.

3. doc/eng_sys_checks.md — Remove non-existent scripts/devops_tasks/build_packages.py

Issue: "Steps to manually run regression test locally" instruction referenced ./scripts/devops_tasks/build_packages.py which does not exist at that path in the repository.
Fix: Replaced with python -m build sdk/(service-name)/(package-name) --outdir (out-folder).

4. doc/dev/static_type_checking.md — Fix py.typed pyproject.toml section name

Issue: Instructed users to add pytyped = ["py.typed"] under [tool.azure-sdk-build], but the correct section (as verified in sdk/core/azure-core/pyproject.toml and sdk/template/azure-template/pyproject.toml) is [tool.setuptools.package-data].
Fix: Corrected section name from [tool.azure-sdk-build] to [tool.setuptools.package-data].

5. doc/dev/tests.md — Update packaging file list and Python minimum version

Issue (packaging files): Listed setup.py and setup.cfg as the mandatory SDK package files, but the current template (sdk/template/azure-template/) uses pyproject.toml with no setup.py or setup.cfg.
Fix: Replaced both entries with a single pyproject.toml entry.

Issue (Python version): Stated "Python 3.8+" as the minimum SDK version throughout, but azure-core, azure-template, and tool_usage_guide.md all specify >=3.9 as the current minimum. The Windows Store version list also omitted Python 3.13 and included the EOL Python 3.8.
Fix: Updated all references to reflect Python 3.9+ as the minimum; updated the Windows Store version list accordingly.

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Verification

• All changed file paths, script names, and section names were verified against actual files in the repository.
• pyproject.toml for azure-core and azure-template confirm the [tool.setuptools.package-data] section name and >=3.9 requirement.
• tool_usage_guide.md states: "The monorepo requires a minimum of python 3.9."
• build_package.py and scripts/devops_tasks/build_packages.py confirmed absent from the repository.

Generated by Documentation Consistency Check · ◷

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