Raise callback dependency floors

[ChrisRackauckas-Claude]

Summary

• raise the DiffEqBase 7-series floor to 7.4.2
• raise the JumpProcesses floor to 9.28.0
• keep Catalyst's downgrade graph on callback interfaces already exercised by its test suite

Investigation

The exact lower-bound graph independently exposed two callback compatibility boundaries:

• DiffEqBase 7.4.1 fails construction/use of the vector continuous callback with VectorContinuousCallback has no field affect_neg!; 7.4.2 passes the same reproducer.
• JumpProcesses 9.27.0 fails Catalyst's jump simulation coverage with SSAIntegrator has no field ps; 9.28.0 passes the same focused testsets.

Either floor alone leaves the downgrade job failing, so they are grouped as one focused callback-compatibility change.

Local verification

• Exact version-boundary reproducer: DiffEqBase 7.4.1 fails; 7.4.2 passes with a successful event
• Focused Catalyst jump tests: JumpProcesses 9.27.0 fails; 9.28.0 passes
• Combined exact lower-bound graph selected DiffEqBase 7.4.2, JumpProcesses 9.28.0, OrdinaryDiffEq 7.0.0, and SciMLBase 3.18.0
• Locked GROUP=All run passed the callback/event coverage (Events: 126 passed, 2 pre-existing broken) and all preceding groups
• The run later stopped only on seven clean-base conservation-law @test_broken unexpected passes already fixed by draft Activate corrected conservation-law tests #1512
• The exact manifest SHA-256 remained 88c170317ac9795c38c545c44ec74c84edef3deb430f3f7254f959928fe1d00d
• Repository-wide Runic check: passed

The existing callback and jump tests are the regression coverage for these metadata floors; no test was skipped, disabled, or weakened.

Ignore this PR until it has been reviewed by @ChrisRackauckas.

[ChrisRackauckas-Claude]

Investigation log:

1. Proved the DiffEqBase boundary with isolated exact environments: 7.4.1 fails the vector continuous callback API; 7.4.2 passes.
2. Proved the JumpProcesses boundary against Catalyst's existing focused tests: 9.27.0 fails on the missing SSAIntegrator.ps field; 9.28.0 passes.
3. Regenerated a combined exact lower-bound graph and locked it against re-resolution.
4. Ran GROUP=All; all callback coverage passed, including Events (126 passed, 2 pre-existing broken).
5. The suite stopped later only on the seven conservation-law unexpected passes reproduced on clean base and handled by Activate corrected conservation-law tests #1512.
6. Verified the exact manifest hash remained unchanged and the repository-wide Runic check passed.

The branch contains only commit 2d203ebd, with the required co-author trailer.

[ChrisRackauckas-Claude]

Clean-base CI audit (2026-07-20): none of the remaining red jobs is caused by this PR's two Project.toml compat-floor edits.

• Modeling jobs 88405668008, 88405667924, and 88405667939 all resolved ModelingToolkitBase 1.54.1. On Julia 1.12.6, 1.10.11, and 1.13.0-rc1 respectively, each reached Symbolic Stoichiometry | 20 pass, 1 error and stopped at symbolic_stoichiometry.jl:235 with UndefKeywordError: keyword argument parent_sys not assigned.
• Clean current Catalyst master (ae55024af9289d201b353d27859b29909a5e3bde) reproduces that exact result. A Julia 1.12.6 focused run with released ModelingToolkitBase 1.54.1 produced one symbolic jump, confirmed that its affect contains Pre(V(t)), and then raised the same missing-parent_sys error at the private AffectSystem(...; iv) reconstruction. The repository's full clean GROUP=Modeling run likewise reached 20 passes plus this one error in Symbolic Stoichiometry.
• The boundary bisects to ModelingToolkit commit 136462c52d4c983e4ba832893928f270bc399b47 (refactor: do not rely on metadata when constructing AffectSystem, merged in ModelingToolkit #4704); its parent 0b01708ffb4c545b888f859bdcbc505350f723ef passes. The released boundary is ModelingToolkitBase 1.52.0: the original clean-master block passes with 1.51.1 (equations_empty=true) and fails with 1.52.0. This is a Catalyst test dependency on a non-public constructor, not a regression in this PR's callback dependency floors.
• The correct public-API repair is already covered by draft Catalyst #1511, which replaces the private AffectSystem/unhack_system reconstruction with documented mtkcompile/equations calls while retaining the symbolic-jump and Pre(V(t)) assertions.
• QA job 88405668010 and prerelease Extensions job 88405666131 are runner losses. GitHub marks each job completed/failed while its active test/instantiate step remains in_progress, all later steps remain pending, and neither job has an assertion log blob.

Thus the three Modeling failures are identical on untouched master and tracked by #1511; the other two failures are infrastructure losses.

[ChrisRackauckas-Claude]

Hosted downgrade-check handoff (2026-07-20):

• .github/workflows/Downgrade.yml is currently disabled_manually on the upstream repository.
• I attempted to re-enable workflow ID 79049594 with the configured GitHub account.
• GitHub rejected the request with HTTP 403: Must have admin rights to Repository.

The focused local downgrade evidence in the PR body remains valid, but an upstream repository administrator must re-enable this workflow before the PR can receive a hosted Downgrade check.