Drop unsupported Reexport 0.2 compat

[ChrisRackauckas-Claude]

Please ignore this PR until it has been reviewed by @ChrisRackauckas.

Summary

• Require Reexport 1.
• Remove the stale Reexport 0.2 compatibility range, which is already impossible with MATLABDiffEq's SciMLBase floor.

Why

An explicit resolver probe with Reexport 0.2.0 and the existing SciMLBase 3.27 floor is unsatisfiable because SciMLBase 3.x requires Reexport 1.x. The removed range therefore does not represent a valid installation graph.

Validation

The exact Julia 1.10 downgrade resolver completed successfully and selected Reexport 1.2.2. The locked root manifest remained unchanged through the test run (SHA-256 db886938804bbd2a503f828695d9d15403e9a18d3c93e64be2ba584e682ae363).

With the repository's CI-mode MATLAB.jl build path:

• Core interface tests: 40/40 passed.
• Core JET tests: 34/34 passed.
• The existing runtime test explicitly reported that no MATLAB engine was installed and skipped its engine-dependent solves.
• QA: 17 passed, 1 existing configured broken check; Pkg.test() exited successfully.

Additional checks passed:

• Focused Reexport 1.2.2 @reexport macro smoke test.
• Full-repository Runic.
• TOML parse and exact compat assertion.
• git diff --check and one-file diff-scope verification.

[ChrisRackauckas-Claude]

Closing as superseded by #91, which has now merged and contains this PR's exact Drop unsupported Reexport 0.2 compat commit (1a21b08d) together with the independent ModelingToolkit floor. No change from this branch remains unmerged.