feat(config): preserve doc-style comments by default

Strip pass was eating JSDoc/Javadoc blocks. Add default preserve
patterns for /** blocks, /*! banners, /// and //! line docs.
Opt out by overriding preserve in .shush.toml.

internal/config/config.go

@@ -87,6 +87,10 @@ func Default() *Config {
 			"@generated",
 			"DO NOT EDIT",
 			`/^#\s*v\d+(\.\d+)*$/`,
+			`/^\/\*\*/`,
+			`/^\/\*!/`,
+			`/^\/\/\//`,
+			`/^\/\/!/`,
 		},
 		ContextLines: 3,
 	}

internal/config/config_test.go

@@ -85,3 +85,32 @@ func TestShouldPreserveVersionPins(t *testing.T) {
 		}
 	}
 }
+
+func TestShouldPreserveDocComments(t *testing.T) {
+	cfg := Default()
+
+	preserved := []string{
+		"/**\n * JSDoc block\n * @param x foo\n */",
+		"/** single-line doc */",
+		"/*! license banner */",
+		"/// Rust or C# doc comment",
+		"//! Rust inner doc comment",
+	}
+	for _, c := range preserved {
+		if !cfg.ShouldPreserveComment(c) {
+			t.Errorf("doc comment not preserved by default: %q", c)
+		}
+	}
+
+	stripped := []string{
+		"/* plain block comment */",
+		"// plain line comment",
+		"# hash comment",
+		"/*\n * multi-line non-doc block\n */",
+	}
+	for _, c := range stripped {
+		if cfg.ShouldPreserveComment(c) {
+			t.Errorf("non-doc comment wrongly preserved: %q", c)
+		}
+	}
+}