chore: sync __version__ stamp to 2026.8.17.1; drop dead release stamper

[Jammy2211]

Summary

Deliberate manual sync of the frozen source __version__ stamp from 2026.7.23.1 to the latest release 2026.8.17.1, with a comment documenting the freeze design: release wheels are stamped at build time, the git tag is the release truth, and the source literal is deliberately never bumped per release (PyAutoBuild#118/#120 — per-release bump commits were the noise engine behind the June/July 2026 accidental-release cascade).

Part of PyAutoLabs/PyAutoHands#235 (six sibling PRs: five stamp syncs + release-sed guards).
Also removes the dead legacy release stamper script — unreferenced anywhere in the workspace, and its grep -v __version__ line-deletion rewrite would corrupt any future multi-line stamp block.

API Changes

None — internal changes only. The __version__ value syncs to what released wheels already report.

Behavioral note: at 2026.8.17.1 the stamp is >30 days past the current workspace floors (2026.7.9.1), so source checkouts running workspace scripts now see the same check_version staleness warning that pip users on the 2026.8.17.1 wheel already see today (CI sets PYAUTO_SKIP_WORKSPACE_VERSION_CHECK=1; devs can too, or the workspace floors can be bumped when scripts next require newer API).
See full details below.

Test Plan

• ast.parse passes on the edited __init__.py
• Release stamp sed simulated against the new file: stamps cleanly; the new guard (PyAutoHands PR) catches corruption
• Full library test suite at ship time

Full API Changes (for automation & release notes)

Changed Behaviour

• autofit.__version__ — literal synced 2026.7.23.1 → 2026.8.17.1 (matches released wheels; no signature or symbol changes)

Generated by the PyAutoLabs agent workflow.