fix(lsp): match wikilink anchors against raw heading text

`[[Page#Heading text]]` parsed the anchor as the literal string after
`#`, but the index stored each heading's anchor as `slugify(title)`.
The two never compared equal, so every TOC-style anchor link
(`[[#1. Topologia atual]]`, etc.) was reported as a broken anchor and
goto-definition couldn't jump to the right heading either.

Slugify the request before comparing — `slugify` is idempotent on
valid-slug input, so the same code path now accepts both
`[[Page#some-heading]]` (slug form) and `[[Page#Some Heading]]`
(raw text). Applied to diagnostics, navigation, and hover preview so
all three agree on what "an anchor matches a heading" means.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/nuwiki-lsp/tests/link_health.rs

@@ -466,6 +466,60 @@ fn collect_wiki_links_finds_nested() {
     }
 }
 
+// ===== Anchor matching against raw heading text =====
+
+#[test]
+fn anchor_matches_raw_heading_text() {
+    // Users write `[[Page#Some Heading]]` (raw text), the index keys by
+    // slugify form. Slugifying the request before comparison makes both
+    // shapes work.
+    let root = "/tmp/anchor1";
+    let idx = build_index(
+        root,
+        &[
+            ("Home", "[[Target#Some Heading]]\n"),
+            ("Target", "= Target =\n== Some Heading ==\n"),
+        ],
+    );
+    let src = "[[Target#Some Heading]]\n";
+    let ast = parse(src);
+    let diags = diagnostics::link_health(
+        &ast,
+        src,
+        Some(&home_uri(root)),
+        &idx,
+        "Home",
+        LinkSeverity::Warning,
+        true,
+    );
+    assert!(diags.is_empty(), "got: {:?}", diags);
+}
+
+#[test]
+fn anchor_matches_unicode_heading() {
+    // Real-world content: heading with em dash and accented chars.
+    let root = "/tmp/anchor2";
+    let idx = build_index(
+        root,
+        &[
+            ("Home", "[[Target#Homelab — VLANs]]\n"),
+            ("Target", "= Target =\n== Homelab — VLANs ==\n"),
+        ],
+    );
+    let src = "[[Target#Homelab — VLANs]]\n";
+    let ast = parse(src);
+    let diags = diagnostics::link_health(
+        &ast,
+        src,
+        Some(&home_uri(root)),
+        &idx,
+        "Home",
+        LinkSeverity::Warning,
+        true,
+    );
+    assert!(diags.is_empty(), "got: {:?}", diags);
+}
+
 // ===== COMMANDS completeness =====
 
 #[test]