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/src/config.rs

@@ -75,6 +75,18 @@ pub struct WikiConfig {
     pub links_space_char: String,
     /// Rebuild the page's TOC on save when set.
     pub auto_toc: bool,
+    /// Heading text + level for the generated `:VimwikiTOC` section
+    /// (vimwiki's `toc_header` / `toc_header_level`).
+    pub toc_header: String,
+    pub toc_header_level: u8,
+    /// Heading text + level for `:VimwikiGenerateLinks` (`links_header` /
+    /// `links_header_level`).
+    pub links_header: String,
+    pub links_header_level: u8,
+    /// Heading text + level for the no-arg `:VimwikiGenerateTagLinks` index
+    /// (`tags_header` / `tags_header_level`).
+    pub tags_header: String,
+    pub tags_header_level: u8,
     /// HTML export options.
     pub html: HtmlConfig,
 }
@@ -196,6 +208,12 @@ impl WikiConfig {
             list_margin: d.list_margin,
             links_space_char: d.links_space_char,
             auto_toc: d.auto_toc,
+            toc_header: d.toc_header,
+            toc_header_level: d.toc_header_level,
+            links_header: d.links_header,
+            links_header_level: d.links_header_level,
+            tags_header: d.tags_header,
+            tags_header_level: d.tags_header_level,
             html: HtmlConfig::default(),
         }
     }
@@ -226,6 +244,12 @@ impl WikiConfig {
             list_margin: d.list_margin,
             links_space_char: d.links_space_char,
             auto_toc: d.auto_toc,
+            toc_header: d.toc_header,
+            toc_header_level: d.toc_header_level,
+            links_header: d.links_header,
+            links_header_level: d.links_header_level,
+            tags_header: d.tags_header,
+            tags_header_level: d.tags_header_level,
             html,
         }
     }
@@ -322,6 +346,18 @@ fn default_listsym_rejected() -> String {
     "-".to_string()
 }
 
+fn default_toc_header() -> String {
+    "Contents".to_string()
+}
+
+fn default_links_header() -> String {
+    "Generated Links".to_string()
+}
+
+fn default_tags_header() -> String {
+    "Generated Tags".to_string()
+}
+
 fn default_links_space_char() -> String {
     " ".to_string()
 }
@@ -348,6 +384,12 @@ fn wiki_defaults() -> WikiDefaults {
         list_margin: -1,
         links_space_char: default_links_space_char(),
         auto_toc: false,
+        toc_header: default_toc_header(),
+        toc_header_level: 1,
+        links_header: default_links_header(),
+        links_header_level: 1,
+        tags_header: default_tags_header(),
+        tags_header_level: 1,
     }
 }
 
@@ -367,6 +409,12 @@ struct WikiDefaults {
     list_margin: i32,
     links_space_char: String,
     auto_toc: bool,
+    toc_header: String,
+    toc_header_level: u8,
+    links_header: String,
+    links_header_level: u8,
+    tags_header: String,
+    tags_header_level: u8,
 }
 
 impl Config {
@@ -593,6 +641,18 @@ struct RawWiki {
     links_space_char: Option<String>,
     #[serde(default, deserialize_with = "opt_bool_or_int::deserialize")]
     auto_toc: Option<bool>,
+    #[serde(default)]
+    toc_header: Option<String>,
+    #[serde(default)]
+    toc_header_level: Option<u8>,
+    #[serde(default)]
+    links_header: Option<String>,
+    #[serde(default)]
+    links_header_level: Option<u8>,
+    #[serde(default)]
+    tags_header: Option<String>,
+    #[serde(default)]
+    tags_header_level: Option<u8>,
 }
 
 impl From<RawWiki> for WikiConfig {
@@ -654,6 +714,12 @@ impl From<RawWiki> for WikiConfig {
             list_margin: r.list_margin.unwrap_or(d.list_margin),
             links_space_char: r.links_space_char.unwrap_or(d.links_space_char),
             auto_toc: r.auto_toc.unwrap_or(d.auto_toc),
+            toc_header: r.toc_header.unwrap_or(d.toc_header),
+            toc_header_level: r.toc_header_level.unwrap_or(d.toc_header_level),
+            links_header: r.links_header.unwrap_or(d.links_header),
+            links_header_level: r.links_header_level.unwrap_or(d.links_header_level),
+            tags_header: r.tags_header.unwrap_or(d.tags_header),
+            tags_header_level: r.tags_header_level.unwrap_or(d.tags_header_level),
             html,
         }
     }