fix(review): close all 2026-06-03 codebase-review findings (R1-R18)

Resolves the 18 findings from the parallel codebase review, tracked in
development/vimwiki-gap.md.

Correctness / perf:
- Wiki.config -> Arc<WikiConfig> so cloning a Wiki is a refcount bump (R5)
- WorkspaceIndex::remove is no longer O(n^2): a per-source contributions
  map limits the scan to buckets the source actually wrote into (R6)
- render_color now expands color_tag_template (__STYLE__/__CONTENT__),
  consuming the previously-dead field; ColorNode documented as an
  extension point; 3 renderer tests added (R3/R4)
- wiki_root_for returns empty/nil on no-match instead of falling back to
  the first wiki (R2); auto_header honours links_space_char (R7)

Cleanup / dedup:
- Remove dead #[allow(dead_code)] stubs + uncalled pub helpers, narrow
  imports (R10/R11)
- Dedup span_of_inline x3 -> InlineNode::span() (R12)
- diary_step single read lock; page_captions single pass (R13)
- Lua auto_header loop -> wiki_list(); detect_current_symbol cleanup
  (R14/R18)

Client / docs:
- :VimwikiNormalizeLink Vim cmds -> <q-args> (R17); ftplugin header fix
  (R16); vars.vim multi-wiki limitation documented (R15)
- Document 19 config options in README.md + doc/nuwiki.txt; fix
  list_margin/shiftwidth doc and stale comments (R1/R9)
- R8 investigated, confirmed not a real bug (documented)

Verified: Neovim harness 307, Vim harness 301/18/21, Rust suite 568, all
0 failed; clippy clean; fresh parallel-agent audit found no regressions.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/nuwiki-lsp/tests/commands_lists.rs

@@ -254,7 +254,8 @@ fn remove_checkbox_none_without_checkbox() {
 fn change_level_indents_single_item() {
     let src = "- one\n- two\n";
     let ast = parse(src);
-    let edit = ops::change_level_edit(src, &ast, &uri(), 1, 1, false, true, false, &[]).expect("edit");
+    let edit =
+        ops::change_level_edit(src, &ast, &uri(), 1, 1, false, true, false, &[]).expect("edit");
     let edits = &edit.changes.unwrap()[&uri()];
     assert_eq!(edits.len(), 1);
     // delta=1 → +2 spaces
@@ -286,7 +287,10 @@ fn cycle_bullets_rotates_glyph_on_indent() {
         .map(|e| e.new_text.clone())
         .collect();
     assert!(texts.contains(&"  ".to_string()), "indent edit: {texts:?}");
-    assert!(texts.contains(&"*".to_string()), "glyph rotated to *: {texts:?}");
+    assert!(
+        texts.contains(&"*".to_string()),
+        "glyph rotated to *: {texts:?}"
+    );
 }
 
 #[test]
@@ -301,14 +305,18 @@ fn cycle_bullets_off_leaves_glyph() {
         .map(|e| e.new_text.clone())
         .collect();
     // Only the indent edit; no glyph rewrite.
-    assert!(!texts.iter().any(|t| t == "*"), "no glyph change: {texts:?}");
+    assert!(
+        !texts.iter().any(|t| t == "*"),
+        "no glyph change: {texts:?}"
+    );
 }
 
 #[test]
 fn change_level_whole_subtree_walks_descendants() {
     let src = "- parent\n  - child a\n  - child b\n- sibling\n";
     let ast = parse(src);
-    let edit = ops::change_level_edit(src, &ast, &uri(), 0, 1, true, true, false, &[]).expect("edit");
+    let edit =
+        ops::change_level_edit(src, &ast, &uri(), 0, 1, true, true, false, &[]).expect("edit");
     let edits = &edit.changes.unwrap()[&uri()];
     // Parent + 2 children get indented. Sibling stays.
     assert!(edits.len() >= 3, "got {} edits", edits.len());

crates/nuwiki-lsp/tests/html_export.rs

@@ -287,7 +287,10 @@ fn render_page_html_ignore_newline_controls_soft_breaks() {
     )
     .unwrap();
     assert!(br.contains("alpha<br />beta"), "para <br>: {br}");
-    assert!(br.contains("one<br />two") || br.contains("one<br />  two"), "list <br>: {br}");
+    assert!(
+        br.contains("one<br />two") || br.contains("one<br />  two"),
+        "list <br>: {br}"
+    );
 }
 
 #[test]

crates/nuwiki-lsp/tests/link_health.rs

@@ -328,7 +328,10 @@ fn generated_links_caption_emits_first_heading() {
     assert!(out.contains("- [[Notes]]"), "fallback: {out}");
     // Without the caption map, both are bare.
     let bare = ops::build_links_text(&pages, "Generated Links", 1, None, 0, None);
-    assert!(bare.contains("- [[About]]") && !bare.contains("About Us"), "bare: {bare}");
+    assert!(
+        bare.contains("- [[About]]") && !bare.contains("About Us"),
+        "bare: {bare}"
+    );
 }
 
 #[test]