fix: standardize package license metadata and documentation links

[hadrien]

Problem

• Deprecated setuptools license configuration disables license inclusion in distributions.
• The implicit build backend leaves license metadata support dependent on the installed setuptools version.
• Package documentation links point to the repository instead of the documentation site.

Solution

• Declare the MIT SPDX expression and LICENSE file using standard project metadata.
• Pin the setuptools build backend to version 84.0.0.
• Remove the deprecated empty license-files override.
• Point Homepage and Documentation to the published documentation site.

Next

• N/A

Bead: fs-wqi

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (ca3b7b6) to head (04627e5).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #176   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines          133       133           
  Branches         7         7           
=========================================
  Hits           133       133           

Flag	Coverage Δ
fastapi-post121	97.74% <ø> (ø)
fastapi-pre121	100.00% <ø> (ø)
python-3.12	100.00% <ø> (ø)
python-3.13	100.00% <ø> (ø)
python-3.14	100.00% <ø> (ø)
sqlmodel	96.24% <ø> (ø)

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