fix: Allow non-recursive Turbo commands in root tasks (#14814)
Fixes #14795.
Root tasks currently reject any script containing the word `turbo`,
including `echo turbo` and `turbo boundaries`, even though neither runs
tasks.
Update the guard to distinguish printed arguments from executable
commands and allow known inspection commands. Handle quoted commands,
compound scripts, and supported package-manager wrappers while keeping
`run`, `watch`, shorthand tasks, and unfamiliar shell syntax guarded.
Add regression coverage for both reported failures, inspection commands,
genuine recursion, and package scripts that could be mistaken for
execution wrappers. Verify recursive scripts are rejected before
execution.
**Validation:** Linux unit and CLI tests, native Windows execution using
a GNU build, Clippy, formatting, and diff checks passed. Windows/MSVC
has not been tested.
