test(11.1-07): planted fixtures and unit tests for fence, execution and name-form holes

- eighteen violation plants pin nested src=, Go aliases, unrun examples, build membership and command forms
- unit tests cover fence collection, captions, goLang, go doc -c, commandWord and Sync

internal/docsite/testdata/violations/snippet-example-no-output-helper/docs/extras/faq.md

@@ -0,0 +1,19 @@
+---
+title: FAQ
+description: "Questions about the demo."
+section: extras
+order: 20
+---
+# FAQ
+
+## Does it migrate
+
+Yes, run `./bin/demo migrate`, then `summer docs:sync` after a source change.
+
+```text
+summer not:checked in a text fence
+```
+
+```go src=modules/demo/never_test.go#neverRunHelper
+func neverRunHelper() {}
+```

internal/docsite/testdata/violations/snippet-example-no-output-helper/modules/demo/never_test.go

@@ -0,0 +1,7 @@
+package demo_test
+
+func Example_neverRun() {
+	neverRunHelper()
+}
+
+func neverRunHelper() {}

internal/docsite/testdata/violations/snippet-example-no-output-helper/want.txt

@@ -0,0 +1,3 @@
+rule: snippet
+file: docs/extras/faq.md
+message: fragment is not inside a Test or Example function