Pass the first Experimental Vertical Milestone end to end

Parent: #8
Blocked by: #41 and #24

Outcome

Prove the complete first Experimental Vertical Milestone after the generic compiler subsystem gates pass.

Acceptance criteria

• FSharp2 compiles the unchanged, pinned IcedTasks Compatibility Corpus across the four declared producer target frameworks through the real Release CoreCompile path.
• Production code contains no branches keyed to IcedTasks paths, namespaces, declarations, target frameworks, source order, or expected failures.
• The milestone passes declared diagnostic, API, F# metadata, deterministic artifact, downstream consumer, runtime, debugger, implementation/reference assembly, resource/signing, and both NativeAOT gates.
• The mandatory implementation-only and public-inline Warm edits prove declaration-aware reuse and clean-compile equivalence.
• #24 supplies admitted governed Cold and Warm measurements only after correctness, artifact, no-fallback, lineage, and evidence checks pass.
• Any newly discovered F# construct first receives generic positive and negative conformance programs in its owning subsystem issue.
• Passing this milestone does not imply the final language-version, compiler-option, diagnostic, platform, or provider Compatibility Gate.

Decision inputs

Issues #3 through #7, #12, and #15 through #19; ADRs 0002, 0008, 0009, 0010, 0020, and 0022.

This is the only #8 child whose acceptance boundary is the IcedTasks Compatibility Corpus.

Start with parent issue #8 and the blockers #41 and #24, then read decision inputs #3–#7, #12, #15–#19 and ADRs 0002, 0008, 0009, 0010, 0020, and 0022. The stated entry point is the real Release CoreCompile path using the pinned IcedTasks Compatibility Corpus across four producer target frameworks. Done means all listed correctness, artifact, runtime, debugger, assembly, resource/signing, NativeAOT, and governed measurement gates pass without IcedTasks-specific production branches.