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-callout-drift/docs/extras/faq.md

@@ -0,0 +1,20 @@
+---
+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
+```
+
+> [!TIP]
+> ```go src=modules/demo/example_test.go#ExampleHello
+> BOGUS
+> ```

internal/docsite/testdata/violations/snippet-callout-drift/want.txt

@@ -0,0 +1,3 @@
+rule: snippet
+file: docs/extras/faq.md
+message: modules/demo/example_test.go#ExampleHello: src= code block must be a top-level block