feat(config): configurable generated-section captions (P2)

TOC / links / tags section headings (and their levels) were hardcoded.
Added per-wiki toc_header/toc_header_level, links_header/links_header_level,
tags_header/tags_header_level — defaults Contents / Generated Links /
Generated Tags at level 1, matching upstream (also fixes the tags index
heading: Tags -> Generated Tags).

A caption_line(name, level) helper emits the `=`-markers; the configured
text + level thread through toc_edit / links_edit / tag_links_edit and the
auto_toc save hook. find_section_range matches the configured text, so
regeneration stays idempotent at any level.

Tests: captions_honour_custom_header_and_level (link_health) + config
round-trip + default assertions (index_and_config); existing tag/toc/links
tests updated for the new arity and the Generated Tags default. fmt/clippy
clean (8-arg ops get allow(too_many_arguments), matching the codebase
precedent); 0 Rust test failures; config-parity green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/nuwiki-lsp/tests/commands_coverage.rs

@@ -298,7 +298,7 @@ fn nuwiki_toc_generates_nested_contents() {
     let src = "= Top =\n== Sub ==\ntext\n";
     let doc = parse(src);
     let uri = Url::from_file_path("/wiki/Page.wiki").unwrap();
-    let edit = ops::toc_edit(src, &doc, &uri, true).expect("toc edit produced");
+    let edit = ops::toc_edit(src, &doc, &uri, true, "Contents", 1).expect("toc edit produced");
     assert!(edit.changes.is_some() || edit.document_changes.is_some());
 
     let toc = ops::build_toc_text(
@@ -307,6 +307,7 @@ fn nuwiki_toc_generates_nested_contents() {
             (2, "Sub".into(), "sub".into()),
         ],
         "Contents",
+        1,
     );
     assert!(toc.contains("= Contents ="));
     assert!(toc.contains("- [[#top|Top]]"));
@@ -317,7 +318,7 @@ fn nuwiki_toc_generates_nested_contents() {
 #[test]
 fn nuwiki_generate_links_lists_all_pages_excluding_current() {
     let pages = vec!["About".to_string(), "Home".to_string(), "Notes".to_string()];
-    let text = ops::build_links_text(&pages, "Links", Some("Home"));
+    let text = ops::build_links_text(&pages, "Links", 1, Some("Home"));
     assert!(text.contains("= Links ="));
     assert!(text.contains("- [[About]]"));
     assert!(text.contains("- [[Notes]]"));
@@ -326,7 +327,7 @@ fn nuwiki_generate_links_lists_all_pages_excluding_current() {
     let src = "= Existing =\n";
     let doc = parse(src);
     let uri = Url::from_file_path("/wiki/Home.wiki").unwrap();
-    assert!(ops::links_edit(src, &doc, &uri, "Home", &pages, true).is_some());
+    assert!(ops::links_edit(src, &doc, &uri, "Home", &pages, true, "Generated Links", 1).is_some());
 }
 
 // :NuwikiCheckLinks — surface broken links across the workspace.
@@ -383,21 +384,31 @@ fn nuwiki_generate_tag_links_builds_section() {
     );
     let by_tag = ops::tag_pages_snapshot(&idx);
 
-    let single = ops::build_tag_links_text(&by_tag, Some("alpha")).unwrap();
+    let single = ops::build_tag_links_text(&by_tag, Some("alpha"), "Generated Tags", 1).unwrap();
     assert!(single.starts_with("= Tag: alpha ="));
     assert!(single.contains("- [[Home]]"));
     assert!(single.contains("- [[Work]]"));
 
     // No-arg variant emits a section per tag.
-    let all = ops::build_tag_links_text(&by_tag, None).unwrap();
-    assert!(all.starts_with("= Tags ="));
+    let all = ops::build_tag_links_text(&by_tag, None, "Generated Tags", 1).unwrap();
+    assert!(all.starts_with("= Generated Tags ="));
     assert!(all.contains("== alpha =="));
     assert!(all.contains("== beta =="));
 
     let src = "= Home =\n";
     let doc = parse(src);
     let uri = Url::from_file_path("/wiki/Home.wiki").unwrap();
-    assert!(ops::tag_links_edit(src, &doc, &uri, Some("alpha"), &by_tag, true).is_some());
+    assert!(ops::tag_links_edit(
+        src,
+        &doc,
+        &uri,
+        Some("alpha"),
+        &by_tag,
+        true,
+        "Generated Tags",
+        1
+    )
+    .is_some());
 }
 
 // :NuwikiRebuildTags — force a full workspace re-index. A rebuild must