[mlakolar]

This prepares for the CovarianceSelection PR that moves fusedGraphicalLasso! onto ProximalSolvers' ADMMSolver. It uses ProximalBase's new SliceSum and FiberSum (mlakolar/ProximalBase.jl#63), which aren't registered yet, so CovarianceSelection's master will require ProximalBase 0.5.3 from GitHub.

DiffPrecTest takes CovarianceSelection from its master. [sources] apply only to the active project, so DiffPrecTest must take ProximalBase from GitHub as well, or its environments would resolve the registered 0.5.2 and fail CovarianceSelection's compat. This PR adds that:

• ProximalBase = {url = …, rev = "master"} in [sources] of Project.toml, benchmark/compare/new/ and exper/;
• ProximalBase in the Julia 1.10 CI step, in the same Pkg.add call as ProximalSolvers and CovarianceSelection;
• the 1.10 setup line in exper/README.md.

DiffPrecTest's own compat stays ProximalBase = "0.5", which master (0.5.3) satisfies. It should merge before the CovarianceSelection PR, so that DiffPrecTest's CI keeps passing when that one lands.

Pkg.test() with --depwarn=error passes on Julia 1.13.2 against ProximalBase master: 20172 tests.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.45%. Comparing base (954b382) to head (23193ac).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #10   +/-   ##
=======================================
  Coverage   98.45%   98.45%           
=======================================
  Files          12       12           
  Lines        1294     1294           
=======================================
  Hits         1274     1274           
  Misses         20       20           

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