The Terminal's compiler service is checked rather than warned about (#1100)

[Rafael-SOWNet]

Closes #1100, which asked for "an hour of someone running the Terminal against something non-trivial" rather than a fix.

The answer: it is benign

A kernel built on the shipped pair — FSharp.Compiler.Service 43.9.300 beside FSharp.Core 10.1 — compiles sixteen of sixteen language features that the compiler service has to implement rather than the parser fold:

generic functions, inference, inline constraints	✅
records, discriminated unions, classes with members, units of measure	✅
async, sequence expressions, list comprehensions	✅
active patterns, tuple destructuring, Option	✅
recursion, sprintf, string interpolation, object expression over an interface	✅

And it still refuses what it should — a type error and a syntax error, each with the position the Terminal shows to whoever typed it. A compiler that accepted everything would pass the first sixteen and be useless, so that half is asserted too.

What changed, and why it is not just a suppression

The warning is suppressed, and the claim it was making now lives in CompilerServiceWorksTest. That is the point of the change rather than a side effect. A warning nobody reads is not a check, and this one had been passing through CI unread for two releases at sixteen occurrences a run. If FSharp.Core or FSharp.Compiler.Service moves and the pair really does come apart, a test fails — where before a sixteen-line warning would have scrolled past again.

InteractiveTest.yml already runs TerminalUnitTests, so this gates on every PR touching it.

Suppressing rather than pinning, because the constraint cannot be met. The 10.1 is the FSharp.Core the F# SDK references implicitly for every F# project; satisfying FSharp.Compiler.Service's = 9.0.300 would mean pinning two majors back, against the SDK, across the whole graph.

The .fsproj comment records what was measured and says the test is what to believe if the versions move.

Measured

	before	now
dotnet pack, NU1608	16	0
dotnet pack, NuGet warnings of any kind	16	0
TerminalUnitTests	7 pass	28 pass

One thing found on the way, filed separately

The tests use a bare kernel deliberately. The Terminal opens AngouriMath.Interactive.AggressiveOperators over the top, which rebinds < > <= >= = <> to build expressions — that is the tool's whole point, and it means ordinary F# containing a comparison does not typecheck once AngouriMath is enabled:

let rec fib n = if n < 2 then n else fib (n-1) + fib (n-2)
  -> typecheck error: expected 'bool' but here has type 'Entity'

Same for if 1 < 2 then … and List.filter (fun x -> x > 1). That is a deliberate design trade-off rather than a defect of this pairing, so it is filed as its own issue rather than smuggled in here.

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