feat(config): add cobra-probe-enabled toggle option and safeguard cobra probing (#133)

currently, every command that doesn't have a completion spec is assumed
to be a cobra cli and it gets ran with a `__complete` argument. for non
cobra clis this can cause problems if those non-cobra clis have
sideeffects even when ran with the `__complete` argument, and there is
no way to disable this.
one of these problems was solved at #111, but a full solution would
probably require actual sandboxing which is i think is an overkill just
for attempting to get suggestions for unrecognized commands. instead of
sandboxing, this pr adds a config option for allowing only selected
commands to be probed and disallowing the rest.
currently the default is still allowing all (`["*"]`) so default
behavior is the same, but it might be better to just have a long list of
known cobra clis as the default instead.

here's a demo of a side effect caused by the probing, in this case
"deleting" a file with rmtrash without actually trying to run the
command:

https://github.com/user-attachments/assets/5256d363-5291-42e8-bb4f-cf7467927246

---------

Co-authored-by: shemishtamesh <shemishtamail@gmail.com>

internal/config/config_test.go

@@ -27,6 +27,9 @@ func TestDefaultConfigAndState(t *testing.T) {
 	if cfg.AI.Providers != nil {
 		t.Errorf("expected default providers map to be nil, got %v", cfg.AI.Providers)
 	}
+	if !cfg.Core.CobraProbeEnabled {
+		t.Errorf("expected cobra probing to be enabled by default")
+	}
 
 	// test manual provider registration
 	cfg.AI.Provider = "custom"