Skip build issues don't necessarily go away when you turn on `SKIP_ACTION = none` and `SKIP_ZERO = 1`

Checkout https://github.com/dfabulich/skip-none-repro which includes a Swift compilation failure.

To repro

1. git switch initial-commit
2. Build the project in Xcode. It will build without error.
3. git switch compile-failure (adding a compile failure)
4. Build the project in Xcode. The Swift compiler will flag the failures and the Skip transpiler will flag them, too, with two errors and a warning.

   /private/tmp/tp/skip-none-repro/Sources/SkipNoneRepro/ContentView.swift:47:24 Skip is unable to determine the owning type for member 'footnote'. This often occurs when other issues prevent Skip from matching the surrounding API call, and it may resolve when those issues are fixed. Or add the owning type explicitly (e.g. MyType.footnote)

   /private/tmp/tp/skip-none-repro/Sources/SkipNoneRepro/ContentView.swift:47:43 Skip is unable to determine the owning type for member 'regular'. This often occurs when other issues prevent Skip from matching the surrounding API call, and it may resolve when those issues are fixed. Or add the owning type explicitly (e.g. MyType.regular)

   /private/tmp/tp/skip-none-repro/Sources/SkipNoneRepro/ContentView.swift:48:18 Skip is unable to match this API call to determine whether it results in a View. Consider adding additional type information

5. git switch main (setting SKIP_ACTION=none and SKIP_ZERO=1)
6. Build the project in Xcode.

Expected: Since Skip is disabled, the Skip errors should go away
Actual: The Skip errors remain

7. "Clear all issues" and build.

Expected: Since Skip is disabled, the Skip errors should not return
Actual: The Skip errors come back.

The only workaround I can find to make the Skip errors go away is to Clean Build Folder, which then takes a long time to rebuild.

Start with the skip-none-repro repository, comparing the initial-commit, compile-failure, and main branches, especially Sources/SkipNoneRepro/ContentView.swift. Reproduce the Xcode builds with SKIP_ACTION=none and SKIP_ZERO=1, including clearing issues, then trace how the Skip errors persist. Done means disabled Skip diagnostics do not return without requiring Clean Build Folder.