Drop Python 3.9 support #117

Context

The workspace is retiring Python 3.9 support. GitHub Actions ubuntu-latest is moving to Ubuntu 26.04, for which actions/setup-python does not provide CPython 3.9 builds. CPython 3.10 builds are available.

Scope

Raise the Python minimum and Ruff target to 3.10; update all Qt test matrices and live/generated documentation; apply safe 3.10-only typing cleanup. Retain tomli for Python 3.10 and preserve historical parser fixtures.

Delivery and acceptance

• Target branch: master.
• One dedicated PR for this repository, linked to this issue; preserve unrelated changes and published historical artifacts.
• Validate changed behavior and metadata on the retained runtimes; report exact results and unavailable checks.
• Keep ubuntu-latest; do not globally upgrade dependency bounds or add Python 3.15 support.
• Merge only after applicable checks pass on the current PR head and branch protections are satisfied. Where no PR CI exists (Camera, Pulse and platform docs), documented local validation is the explicitly approved gate.
• Close this issue only after the corresponding PR is verified as merged. No package release or promotion to another stable branch is authorized by this task.