[thomasjm]

Picks up codedownio/notebook-language-server-core#6, which transforms textDocument/selectionRange, semanticTokens/full and /range, and the goto family. Those had no arms, so they reached the client in shadow coordinates and goto pointed at files in the shadow crate.

Also adds test/Test/CodeAction.hs, running the code action response path through the real StripDirective :> HeadTailTransformer rather than a stand-in. An edit rust-analyzer put on shadow line 8 comes back on notebook line 7, over both textDocument/codeAction and codeAction/resolve, plus the cases that get dropped: a wrapper line, another file in the shadow crate, a file creation. A plain .rs file takes idTransformerParams and must not shift at all.

That answers an off-by-one seen against 0.2.5.0 in codedown, where a quick fix landed on the line below. It isn't this repo and it isn't the transformer composition: 0.2.5.0's textDocument/codeAction arm only filtered actions and never touched the edit, and it had no codeAction/resolve arm. The untransform arrived in 0.2.6.0. Downstream just needs a newer version, which 0.2.7.0 is.

Last commit switches the suite to sandwich-discover, the way notebook-language-server-core does it, so a new test/Test/*.hs exporting tests is picked up without editing Main.hs. Modules under test/Test renamed spec to tests to match.