Allow intentional CommonSolve solve reexport in QA

[ChrisRackauckas-Claude]

Ignore this PR until reviewed by @ChrisRackauckas.

Summary

• Assert that FiniteVolumeMethod's intentional public re-export set is exactly [:solve].
• Allow that one CommonSolve-owned binding in SciMLTesting's default public re-export audit.
• Keep the re-export audit enabled so any additional dependency-owned public binding still fails QA.

Root cause

SciMLTesting 2.4.0 enabled the public re-export audit by default. FiniteVolumeMethod intentionally imports and exports CommonSolve's solve generic and defines package-specific methods on it, so clean main began failing the new check even though #126 changed only the downgrade workflow.

The dependency boundary was verified locally on clean merge commit e9fdb36edcdc7a8a528d47b19aaece5f5da2427e:

• SciMLTesting 2.3.0: QA 18/18 passed.
• SciMLTesting 2.4.0: QA 18 passed, 1 failed; the only finding was reexported == [:solve].

Validation

• Julia 1.12.6, GROUP=QA, SciMLTesting 2.4.0, exact hosted test arguments: QA 20/20 passed.
• Julia 1.10.11 LTS, GROUP=QA, SciMLTesting 2.4.0, exact hosted test arguments: QA 18/18 passed.
• Runic.jl 1.7.0 --check .: exit 0.
• git diff --check: exit 0.

The first local LTS invocation stopped before running tests because an ignored Julia 1.12 manifest from the preceding local run was still present. I removed only that generated manifest and reran from a clean resolution state; the LTS QA result above is from the clean rerun.

[ChrisRackauckas-Claude]

Investigation scratchpad for the clean-main QA failure observed in #126:

• Hosted source: run 29861895811, job 88740532058, head 660ae97783fb208168a82442916042e3b23bbf38. The PR changed only .github/workflows/Downgrade.yml; QA failed 18/19 because SciMLTesting reported reexported == [:solve].
• Clean reproduction: detached current main merge commit e9fdb36edcdc7a8a528d47b19aaece5f5da2427e, Julia 1.12.6, SciMLTesting 2.4.0, GROUP=QA, coverage/check-bounds/depwarn matching Actions. Result: 18 pass, 1 fail, 19 total; exit 1.
• Boundary: SciMLTesting commit 2881f4c15fb715f0934009a800d42765751587b1 enabled the default public re-export audit. Registered 2.3.0 tree 6ebdbe314d25a3dfa1958e93356e61d7f3c0033d passes this clean FVM revision (18/18); registered 2.4.0 tree 7f694d4107f2babd9bd918f56e69564eb7ff44b7 fails only on :solve.
• Intent: FVM imports and exports CommonSolve's solve generic and defines FVM-specific methods on it. The existing QA comment and rendered-doc exception already document that ownership boundary.
• Fix: assert the exact intentional re-export set is [:solve], then pass only that name through reexports_allow; the audit remains enabled for every other binding.

Final local verification on c0dde60ffe34a02946622cbfe5383304cdcbcc02:

• Julia 1.12.6 / SciMLTesting 2.4.0: QA 20/20, exit 0.
• Julia 1.10.11 / SciMLTesting 2.4.0: QA 18/18, exit 0.
• Runic 1.7.0 full repository check: exit 0.
• git diff --check: exit 0.

Workspace-local raw evidence and SHA-256:

• Hosted job log: audit/logs/finitevolumemethod-pr126-run29861895811-job88740532058.log — d90a21d6e34363c5abb6ce65711e0fb60bcfb09403c3056ed0a1c1d0b3e4880e
• Clean 2.4 failure: audit/logs/finitevolumemethod-main-e9fdb36-qa-julia1.12.6.log — 81d673400bef5f3bb639ba4a57a389e5ecd39436fc842d02a41df04cabb20891
• Clean 2.3 control: audit/logs/finitevolumemethod-main-e9fdb36-qa-scimltesting2.3-julia1.12.6.log — 4167256092f2d5a0a737fad8ab42fd67bd0fb4e3267cce62a41d90dcb8c5c7de
• Release boundary: audit/logs/finitevolumemethod-scimltesting-general-release-boundary.log — cf6986a5bd06224b38bec0eff057ab266a37b6ab5a17595adfbbb3ead71432cb
• Final Julia 1.12.6 QA: audit/logs/finitevolumemethod-allow-solve-reexport-qa-julia1.12.6-final.log — 4109dc6cb9dee6c3938a48f74d210fbf8c79c1728565ab6a7be2bfa73718fe21
• Final Julia 1.10.11 QA: audit/logs/finitevolumemethod-allow-solve-reexport-qa-julia1.10.11-final.log — 12ff1772d519f57c12d1962e53b4bebe093817638836a51ad59191eef8f507f2
• Final Runic: audit/logs/finitevolumemethod-allow-solve-reexport-runic-final.log — 81d9441282d557d26687b37847c322e544391af1cee98045136b912d641313cc

[ChrisRackauckas-Claude]

Post-timer CI classification at immutable head c0dde60ffe34a02946622cbfe5383304cdcbcc02:

• Target QA job 88777224627 passed: QA | 20 / 20 | 31.9s; the complete job passed in 16m25s.
• Downgrade, documentation, Runic, spellcheck, Runic suggestions, detect, and Julia-current Core passed.
• Julia LTS Core job 88777224570 and Julia prerelease Core job 88777224625 did not report test failures. Both ran on self-hosted-4vcpu-8gb runners, left the test step in_progress, and ended only with the self-hosted-runner-lost-communication annotation.
• This PR changes only test/qa/qa.jl; those Core runner losses are independent of the focused QA fix and require a separate clean-base infrastructure follow-up. No Core test was skipped, silenced, or changed here.

Archived evidence:

• QA hosted log SHA-256: eb9baa6f53b1b1860b8164d6a65c93d495ea0798ff45cedb1ba4e8c7d393fb5a
• QA job metadata SHA-256: d03249df62f89838efc40221f648d995464b7175c7fbbc34197a240532a495ac
• LTS runner-loss metadata SHA-256: 2e08c7752a7b5d78ee7c1a4055a1bd082d4afb751af1870a5cd556e5bb30eb6e
• Prerelease runner-loss metadata SHA-256: a17752815c51ae088c1fb16ad0d2ce61d7e3da733057f948c45b051b6ab3d064