feat(lsp): wire diary/auto_toc/links_space_char/list_margin; drop client-side keys

Consume several per-wiki config keys that the server deserialized but
ignored, and remove keys whose effect is purely client-side:

- diagnostics: re-publish open-doc diagnostics on
  didChangeConfiguration so a link_severity change takes effect
  immediately; fix the single-key unwrap in apply_change so a minimal
  `{ diagnostic: {...} }` payload isn't mistaken for a namespace wrapper.
- auto_toc: rebuild an existing TOC section on save (new
  ops::toc_rebuild_edit, no-op when the page has no TOC).
- diary index: honour diary_header, diary_sort and diary_caption_level
  when rendering the diary index body.
- links_space_char: apply on rename so spaces in the link target and
  the on-disk path become the configured glyph (default " " = verbatim).
- list_margin: thread the per-wiki value into render_page_html.
- remove nested_syntaxes, maxhi and diary_start_week_day from the server
  config: nested-syntax and heading highlighting are client-side, and
  the weekly diary is ISO-week based so a custom week start has no clean
  server-side meaning.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/nuwiki-lsp/tests/diary.rs

@@ -274,7 +274,7 @@ fn build_index_body_is_newest_first_grouped_by_year_month() {
         &["2025-12-31", "2026-05-11", "2026-05-12", "2026-04-30"],
     );
     let entries = diary::list_entries(&idx);
-    let body = diary::build_index_body(&entries, "diary", "Diary");
+    let body = diary::build_index_body(&entries, "diary", "Diary", diary::DiarySort::Desc, 1);
     let lines: Vec<&str> = body.lines().collect();
     assert_eq!(lines[0], "= Diary =");
     // First date in output should be the latest: 2026-05-12
@@ -292,10 +292,46 @@ fn build_index_body_is_newest_first_grouped_by_year_month() {
 
 #[test]
 fn build_index_body_empty_when_no_entries() {
-    let body = diary::build_index_body(&[], "diary", "Diary");
+    let body = diary::build_index_body(&[], "diary", "Diary", diary::DiarySort::Desc, 1);
     assert_eq!(body, "= Diary =\n");
 }
 
+#[test]
+fn build_index_body_ascending_sort_lists_oldest_first() {
+    let idx = build_index_with_entries("/tmp/diarySort", &["2026-05-11", "2026-05-12"]);
+    let entries = diary::list_entries(&idx);
+    let body = diary::build_index_body(&entries, "diary", "Diary", diary::DiarySort::Asc, 1);
+    let older = body.find("2026-05-11").unwrap();
+    let newer = body.find("2026-05-12").unwrap();
+    assert!(older < newer, "ascending sort lists oldest first");
+}
+
+#[test]
+fn build_index_body_caption_level_shifts_all_headings() {
+    let idx = build_index_with_entries("/tmp/diaryCap", &["2026-05-11"]);
+    let entries = diary::list_entries(&idx);
+    let body = diary::build_index_body(&entries, "diary", "Diary", diary::DiarySort::Desc, 2);
+    assert!(body.contains("== Diary =="), "caption at level 2");
+    assert!(
+        body.contains("=== 2026 ==="),
+        "year nests one below caption"
+    );
+    assert!(
+        body.contains("==== May ===="),
+        "month nests two below caption"
+    );
+}
+
+#[test]
+fn build_index_body_clamps_caption_level_to_six() {
+    let idx = build_index_with_entries("/tmp/diaryClamp", &["2026-05-11"]);
+    let entries = diary::list_entries(&idx);
+    // caption_level 6 → year/month would be 7/8 but clamp to 6.
+    let body = diary::build_index_body(&entries, "diary", "Diary", diary::DiarySort::Desc, 6);
+    assert!(body.contains("====== Diary ======"));
+    assert!(!body.contains("======="), "no heading exceeds level 6");
+}
+
 #[test]
 fn render_index_body_round_trip() {
     let cfg = wiki_cfg("/tmp/diaryA");
@@ -305,6 +341,23 @@ fn render_index_body_round_trip() {
     assert!(body.contains("[[diary/2026-05-11]]"));
 }
 
+#[test]
+fn render_index_body_honours_custom_header_sort_and_caption() {
+    let mut cfg = wiki_cfg("/tmp/diaryCustom");
+    cfg.diary_header = "Journal".into();
+    cfg.diary_sort = "asc".into();
+    cfg.diary_caption_level = 2;
+    let idx = build_index_with_entries("/tmp/diaryCustom", &["2026-05-11", "2026-05-12"]);
+    let body = diary::render_index_body(&cfg, &idx);
+    assert!(
+        body.contains("== Journal =="),
+        "custom header at caption level 2"
+    );
+    let older = body.find("2026-05-11").unwrap();
+    let newer = body.find("2026-05-12").unwrap();
+    assert!(older < newer, "asc sort honoured");
+}
+
 // ===== is_in_diary =====
 
 #[test]