refactor(tests): group test files by feature, drop phase/cluster naming

Restructures the integration test layout so each file is named after
what it covers, not the implementation phase it landed in.

nuwiki-core (renames only):
  vimwiki_lexer            → lexer
  vimwiki_parser           → parser
  vimwiki_tags             → tags
  vimwiki_table_alignment  → table_alignment
  diary_period             → diary
  list_continuation        → lists
  transclusion_attrs       → transclusion
  + table colspan/rowspan tests moved here from parity_cluster_1

nuwiki-lsp (renames + merges + one split):
  cluster_a_list_rewriters       → commands_lists
  cluster_b_table_rewriters      → commands_tables
  cluster_c_link_helpers +
    phase19_followlink_creates   → commands_links
  phase13_rename_commands        → commands_files
  phase17_colorize               → commands_colorize
  phase17_html_export            → html_export
  phase15_link_health            → link_health
  phase18_multi_wiki             → multi_wiki
  phase19_folding                → folding
  nav                            → navigation
  lsp_helpers                    → helpers
  phase16_diary +
    diary_frequency              → diary
  phase11_plumbing +
    parity_cluster_1 (config)    → index_and_config
  tags_index_and_lsp +
    phase17_backfill             → commands_tags
  phase14_edit_commands          → split into
    commands_checkboxes,
    commands_headings,
    commands_tasks

Net: 30 → 28 integration-test files. 456 → 455 tests (the one
removed test was a dummy `paragraph_render_is_unchanged` whose only
purpose was to keep a `ParagraphNode` import alive in
parity_cluster_1; the import is exercised elsewhere now).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/nuwiki-core/tests/transclusion.rs

@@ -0,0 +1,60 @@
+//! Cluster 8 — transclusion attribute parsing. The basic
+//! `{{url|alt|key=val}}` shape was already wired; this test pins
+//! down quote-stripping on quoted values (`key="quoted value"`)
+//! so an HTML renderer doesn't double-emit `"` artefacts.
+
+use nuwiki_core::ast::{BlockNode, InlineNode};
+use nuwiki_core::render::{HtmlRenderer, Renderer};
+use nuwiki_core::syntax::vimwiki::VimwikiSyntax;
+use nuwiki_core::syntax::SyntaxPlugin;
+
+fn parse(src: &str) -> nuwiki_core::ast::DocumentNode {
+    VimwikiSyntax::new().parse(src)
+}
+
+fn first_transclusion(doc: &nuwiki_core::ast::DocumentNode) -> &nuwiki_core::ast::TransclusionNode {
+    let para = match &doc.children[0] {
+        BlockNode::Paragraph(p) => p,
+        _ => panic!("expected paragraph"),
+    };
+    for child in &para.children {
+        if let InlineNode::Transclusion(t) = child {
+            return t;
+        }
+    }
+    panic!("no transclusion in paragraph");
+}
+
+#[test]
+fn transclusion_attrs_strip_double_quotes() {
+    let doc = parse(r#"{{cat.png|cat|style="border: 1px"}}"#);
+    let t = first_transclusion(&doc);
+    assert_eq!(t.url, "cat.png");
+    assert_eq!(t.alt.as_deref(), Some("cat"));
+    assert_eq!(
+        t.attrs.get("style").map(String::as_str),
+        Some("border: 1px")
+    );
+}
+
+#[test]
+fn transclusion_attrs_strip_single_quotes() {
+    let doc = parse("{{cat.png|cat|class='thumb'}}");
+    let t = first_transclusion(&doc);
+    assert_eq!(t.attrs.get("class").map(String::as_str), Some("thumb"));
+}
+
+#[test]
+fn transclusion_attrs_leave_unquoted_values_alone() {
+    let doc = parse("{{cat.png|cat|width=200}}");
+    let t = first_transclusion(&doc);
+    assert_eq!(t.attrs.get("width").map(String::as_str), Some("200"));
+}
+
+#[test]
+fn transclusion_renders_clean_html_with_quoted_attr() {
+    let doc = parse(r#"{{cat.png|cat|style="border: 1px"}}"#);
+    let out = HtmlRenderer::new().render_to_string(&doc).unwrap();
+    assert!(out.contains(r#"style="border: 1px""#), "got: {out}");
+    assert!(!out.contains("""));
+}