Integrate reviewed dependency updates

[gabeosx]

Integrates the six reviewed Dependabot PRs together while preserving each original PR head in the merge graph:

• Bump peter-evans/create-pull-request from 7 to 8 #19: peter-evans/create-pull-request v8
• Update build requirement from >=1.2 to >=1.5.1 #20: build >=1.5.1
• Update httpx requirement from >=0.27 to >=0.28.1 #21: httpx >=0.28.1
• Update mypy requirement from >=1.10 to >=2.2.0 #22: mypy >=2.2.0
• Update pytest-cov requirement from >=5.0 to >=7.1.0 #23: pytest-cov >=7.1.0
• Update pytest requirement from >=8.2 to >=9.1.1 #24: pytest >=9.1.1

The individual PRs overlap in pyproject.toml, so this branch resolves those mechanical merge conflicts while retaining all intended version floors.

Validation performed on the exact final Git tree:

• Ruff formatting and lint
• Python compilation
• strict mypy 2.3
• 111 offline tests passed, 1 opt-in live test skipped
• 78.64% coverage
• source distribution and wheel builds
• Hermes Agent 0.18.2 wheel install, plugin discovery, setup, TinyFish search/extract selection, and doctor checks
• every original PR individually passed CI and Dependency Review

No release or tag is included.