Do not highlight #number in documents (#26365)

- Currently the post processing will transform all issue indexes (such as `#6`) into a clickable link.
- This makes sense in an situation like issues or PRs,
where referencing to other issues is quite common
and only referencing their issue index is an handy and efficient way to do it.
- Currently this is also run for documents
(which is the user profile and viewing rendered files),
but in those situations it's less common to reference issues by their index and instead could mean something else.
- This patch disables this post processing for issue index for documents. Matches Github's behavior.
- Added unit tests.
- Resolves https://codeberg.org/Codeberg/Community/issues/1120

Co-authored-by: Gusted <postmaster@gusted.xyz>

modules/markup/html_internal_test.go

@@ -262,6 +262,30 @@ func TestRender_IssueIndexPattern5(t *testing.T) {
 	})
 }
 
+func TestRender_IssueIndexPattern_Document(t *testing.T) {
+	setting.AppURL = TestAppURL
+	metas := map[string]string{
+		"format": "https://someurl.com/{user}/{repo}/{index}",
+		"user":   "someUser",
+		"repo":   "someRepo",
+		"style":  IssueNameStyleNumeric,
+		"mode":   "document",
+	}
+
+	testRenderIssueIndexPattern(t, "#1", "#1", &RenderContext{
+		Ctx:   git.DefaultContext,
+		Metas: metas,
+	})
+	testRenderIssueIndexPattern(t, "#1312", "#1312", &RenderContext{
+		Ctx:   git.DefaultContext,
+		Metas: metas,
+	})
+	testRenderIssueIndexPattern(t, "!1", "!1", &RenderContext{
+		Ctx:   git.DefaultContext,
+		Metas: metas,
+	})
+}
+
 func testRenderIssueIndexPattern(t *testing.T, input, expected string, ctx *RenderContext) {
 	if ctx.URLPrefix == "" {
 		ctx.URLPrefix = TestAppURL