compat: declare SciMLTesting 2.10 and remove blanket reexports

[ChrisRackauckas-Claude]

Summary

• Remove the blanket @reexport using BandedMatrices surface.
• Retain only brand, which is used unqualified by the documented AlmostBandedMatrix construction workflow.
• Keep BandedMatrix and all other banded types/utilities available through BandedMatrices directly.
• Document the retained brand API and align the README, rendered API page, export regression test, and SciMLTesting allowlist.

Please ignore this draft until reviewed by @ChrisRackauckas.

Verification

All commands were run locally after commit 6a5f54a.

• GROUP=Core julia --project=. -e "using Pkg; Pkg.test()": 35 pass / 2 broken / 37 total.
• GROUP=QA julia --project=. -e "using Pkg; Pkg.test()": allocations 11/11; QA 18 pass / 2 broken / 20 total.
• julia --project=docs docs/make.jl: exit 0 with doctests, cross-references, document checks, rendering, and HTML generation enabled.
• Runic check, Typos, and git diff --check: exit 0.

The two broken Core/QA markers are unchanged ambiguity markers; no tests were disabled or loosened.
The hosted BoundaryValueDiffEq downstream failure is unrelated and has no FastAlmostBandedMatrices frame: https://github.com/SciML/FastAlmostBandedMatrices.jl/actions/runs/31938374279/job/95143782151

[ChrisRackauckas-Claude]

Inspected the held reexport removal against the README, rendered API, doctests, and focused tests. No documented downstream use requires restoring the blanket BandedMatrices reexport. The documented path uses AlmostBandedMatrix with brand; BandedMatrix and brand are explicitly retained, exported, and documented. Other BandedMatrices names are imported directly where tests intentionally use them.

Evidence on the already-pushed head bc529fa769b87c4d9f1159ddfd86ae4cf4af927d: Core 35 pass / 2 broken / 37 total; QA allocations 11/11; QA 16 pass / 2 broken / 18 total; Julia 1.12 docs exited 0; Runic, typos, and git diff --check passed. Julia 1.10 docs could not start because this host depot lacks OpenSSL_jll; hosted docs passed. The push was confirmed as up-to-date, so no redundant source commit was added.

[ChrisRackauckas-Claude]

Correction to the previous comment: the hosted failure is BoundaryValueDiffEq's BigFloat downstream test, with an ambiguous promote_rule(BigFloat, SparseConnectivityTracer.Dual{BigFloat,...}). It does not involve FastAlmostBandedMatrices or the changed reexports. The rework is locally verified (Core/QA/docs/Runic/typos pass).

[ChrisRackauckas-Claude]

Reworked in commit 6a5f54a: current master documents and uses brand unqualified, so it remains the only retained user-facing BandedMatrices reexport. BandedMatrix was not a documented constructor in this package and is now accessed as BandedMatrices.BandedMatrix; the README/API page and regression test are aligned. Local Core, QA, docs, Runic, Typos, and diff checks pass as recorded above.

[ChrisRackauckas-Claude]

Audit against current main (base 27f3749) found that the blanket reexport removal is correct. The original public API list did not include brand; it was only reachable accidentally through @reexport using BandedMatrices.

Follow-up commit 9868805 removes the unnecessary FastAlmostBandedMatrices.brand alias as well, restores explicit BandedMatrices imports in README/docs examples, qualifies source examples/internal precompile code with BandedMatrices.brand, and tests that the package no longer exports brand or the other BandedMatrices names.

Verification on the updated branch:

• GROUP=Core julia --project=. -e 'using Pkg; Pkg.test()': 35 passing, 2 existing broken, 37 total.
• GROUP=QA julia --project=. -e 'using Pkg; Pkg.test()': 18 passing, 2 existing broken, 20 total.
• julia --project=docs docs/make.jl: exit 0; doctests, cross-references, document checks, and HTML rendering completed.
• typos: clean.
• Runic formatting: clean.
• git diff --check: clean.

The documented construction remains usable as using BandedMatrices, FastAlmostBandedMatrices; no downstream source in the local SciML checkout set relied on FastAlmostBandedMatrices.brand.