feat: trace the termination status inside a Reactant-compiled solve

[gdalle-bot]

This PR was opened by a coding agent, please disregard it until @gdalle has reviewed it

Stacked on #150 (base gd/reac2). Addresses the first bullet of #149.

The problem

ConvergenceStats.termination_status was a plain MOI.TerminationStatusCode, assigned from inside three @trace if blocks. An enum cannot be traced, so only the trace-time value of those assignments survived: a compiled run that converged still reported MOI.OPTIMIZE_NOT_CALLED. max_kkt_passes and time_limit decided when to stop, but the run never said which one had fired.

The fix

Store the status as an integer code:

• ConvergenceStats gains a type parameter and its field becomes termination_status_code::S, an ordinary number. to_rarray tracks it and the compiled program writes it like any other stat.
• termination_status(stats) (@public) decodes it back to a MOI.TerminationStatusCode. solve returns exactly the same status it always did, one call away; the MOI wrapper reads it through the accessor.
• status_code(status) is the encoding direction, used by try_solve_noconstraints!.

The elseif workaround goes away with it. With a traceable code, set_termination_status!! selects the criterion with nested ifelse calls instead of three separate @trace if blocks ordered by increasing priority and relying on last-write-wins (EnzymeAD/Reactant.jl#2563), so the priority between simultaneous criteria is now stated in one place.

Tests

• The Reactant coherence tests compare statuses between the plain and compiled runs, which test: reactivate @stable and check Reactant/plain coherence #153 had to leave out.
• The time limit test checks that the compiled solve reports MOI.TIME_LIMIT, not just that it stops at the right time.

Verified locally on the CPU backend that all three statuses (OPTIMAL, ITERATION_LIMIT, TIME_LIMIT) come back out of a compiled solve!, for both PDHG and PDLP. The Core (5676 pass), MOI (1827 pass) and Reactant (61 pass) test groups are green, and Runic is clean.

Not in scope

The other items of #149 (the uncounted kkt_errors! pass in initialize, the silent record_error_history / show_progress no-ops, the loosened type parameters, coverage) are untouched.

🤖 Generated with Claude Code

https://claude.ai/code/session_01JPzdTAQVAXUNUAQsL4Nz71

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
src/CoolPDLP.jl	100.00% <ø> (ø)
src/MOI_wrapper.jl	99.23% <100.00%> (ø)
src/algorithms/common.jl	97.46% <100.00%> (ø)
src/components/termination.jl	92.30% <100.00%> (-0.55%)	⬇️

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