Close the unterminated @testset in ode_initdt_tests.jl

[ChrisRackauckas-Claude]

This PR should be ignored until reviewed by @ChrisRackauckas.

The failure

test/InterfaceI/ode_initdt_tests.jl does not parse on master:

LoadError: ParseError:
# Error @ test/InterfaceI/ode_initdt_tests.jl:130:5
    @test SciMLBase.successful_retcode(sol_ok)
end
└ ── Expected `end`

The @testset "DAE reversed tspan automatic initdt (#908)" block added in #4001
was never closed. The file's last end closes the for loop inside it, so the
parser reaches EOF still expecting the testset's end.

Blast radius

One missing end, five red jobs on master:

Job	Symptom
tests / InterfaceI (julia lts)	Initdt Tests errored, group failed
tests / InterfaceI (julia 1)	same
tests / InterfaceI (julia pre)	same
Downgrade / Downgrade Tests - InterfaceI	same
format-check / Runic	[954/1017] test/InterfaceI/ode_initdt_tests.jl ✖ (Runic cannot format a file that will not parse)

Because the file never parsed, every assertion in the #908 testset has been
dead since #4001 merged — the integ.dt < 0 regression check that PR was
written to add has never actually executed.

The fix

Add the missing end.

Verification

Ran locally on Julia 1.10 (lts), from a clean checkout of this branch:

$ GROUP=InterfaceI julia --project=. -e 'using Pkg; Pkg.test()'
...
Test Summary: | Pass  Total     Time
Initdt Tests  |   29     29  1m14.6s
...
     Testing OrdinaryDiffEq tests passed

29 passing assertions where master got 15 passed + 1 error — the 14 newly-live
assertions in the #908 testset all pass, so #4001's fix is sound; only its test
was unreachable.

Runic is clean on the file:

$ julia --project=@runic -e 'using Runic; exit(Runic.main(["--check","--diff","test/InterfaceI/ode_initdt_tests.jl"]))'
$ echo $?
0

Relation to other PRs

#4012 bundles this fix together with two unrelated changes. This PR is the
parse fix on its own so it can land and unblock InterfaceI/Downgrade/format-check
independently.

🤖 Generated with Claude Code

https://claude.ai/code/session_01TPHRh64BLfoXSzQ3AxKNwC