fix: validate set and shopt options when reading a Taskfile

[posidoni]

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Follow-up to #2429. The panic from that issue was fixed upstream in mvdan/sh, but an invalid set:/shopt: option is still only reported when a command actually runs — once per command, with no hint about the actual mistake:

task: [default] echo "hello"
shopt: invalid option name "pipefail"
task: Failed to run task "default": exit status 1

This PR validates set and shopt lists when the Taskfile is read (root, task and command level), following the approach of #2892:

task: invalid shopt option "pipefail" (did you mean to put it in "set"?)
file: Taskfile.yml:1:1

• Valid values mirror the interpreter's unexported posixOptsTable/bashOptsTable (mvdan.cc/sh/v3/interp), i.e. exactly what works at runtime.
• shopt: ["-o", "pipefail"] keeps working: a -o entry switches validation of the remaining entries to set options, matching shopt -s -o semantics (covered by a regression test).
• When an option is placed in the wrong list, the error suggests the right one (pipefail → set, globstar → shopt).
• schema.json: the shopt enum was missing three supported options (dotglob, extglob, nocaseglob) — extended to all six; reference docs updated accordingly.

Note on behavior: an invalid option now fails at parse time even if the task declaring it never runs — consistent with other Taskfile validation such as #2892.

Tested with four new tests (an invalid option at each of the three levels, plus the -o regression) and a full go test ./... run.

Disclosure per the AI usage policy: this PR (code and description) was prepared with AI assistance. I reviewed and tested all changes and can explain every line.

[trulede]

IMHO I think it would be better if errors with options were raised by mvdan (which I think does this already, perhaps?) than to have to keep such a list up to date.

End effect would be (is) the same, an error.

[posidoni]

mvdan does raise an error today, but only at runtime, once per command, after Task has already started executing: every command in the task fails with shopt: invalid option name "pipefail" and there is no hint that the option belongs in set:. What I wanted here is the same thing #2892 did for includes: catch it when the Taskfile is read, and point at the right list, which mvdan cannot do since it does not know the set:/shopt: split exists.

On keeping the list up to date: fair point, though we already maintain exactly this list in schema.json for editor completion (it had drifted, this PR brings it back in sync). If a second copy in Go feels wrong, I can drop the list entirely and probe the interpreter at parse time instead: run shopt -s <opt> / set -o <opt> against a throwaway interp.Runner and translate the error. Same early failure, nothing to maintain. Happy to go either way.

[trulede]

I think its reasonable to update the schema.

However, adding programmatic checks would prevent passing new values to mvdan in the future. As it stands now, you get an error from mvdan ... fix the typo ... and move on.