fix(ci): release through protected main

[hadrien]

Problem\n\n- Release commits cannot reach protected main before their required checks exist.\n- The existing PAT is not an administrator bypass actor.\n\n# Solution\n\n- Generate each release commit and tag locally.\n- Run existing CI on a temporary branch for the exact release SHA.\n- Promote the green commit and tag atomically.\n- Publish GitHub release notes and PyPI artifacts from the tag event.\n- Keep the main ruleset and required checks unchanged.\n\nfs-3z4

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.74%. Comparing base (fb282e0) to head (77fd863).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #129   +/-   ##
=======================================
  Coverage   97.74%   97.74%           
=======================================
  Files           1        1           
  Lines         133      133           
  Branches        7        7           
=======================================
  Hits          130      130           
  Misses          3        3           

Flag	Coverage Δ
fastapi-post121	97.74% <ø> (ø)
fastapi-pre121	97.74% <ø> (ø)
sqlmodel	97.74% <ø> (ø)

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