fix(wikilinks): supporte les ancres internes [[#Titre|Texte]] et corrige les IDs de titres

- Ajoute la reconnaissance de la syntaxe Obsidian [[#Titre|Texte]] pour
  créer des liens d'ancre vers les titres du document courant.
- Corrige _heading_slugify pour ignorer les balises HTML et décoder les
  entités HTML (ex. &) avant de générer l'ID, évitant ainsi la
  pollution par les wikilinks placés dans les titres.
- Ajoute le style .wikilink-anchor et des tests couvrant ces cas.

Fixe le rendu du document TestDir/Agents IA - Panorama Complet 2026.md.

backend/main.py

@@ -824,17 +824,23 @@ def _heading_slugify(text: str) -> str:
 
     Matches the JavaScript slugify algorithm exactly using
     Unicode-aware character classification:
-    1. Lowercase
-    2. NFD normalize + strip combining marks
-    3. Keep only Unicode letters, numbers, spaces, hyphens
-    4. Replace spaces with hyphens, collapse multiple hyphens
+    1. Strip HTML tags (e.g. wikilink spans rendered inside headings)
+    2. Decode HTML entities (e.g. ``&`` → ``&``)
+    3. Lowercase
+    4. NFD normalize + strip combining marks
+    5. Keep only Unicode letters, numbers, spaces, hyphens
+    6. Replace spaces with hyphens, collapse multiple hyphens
 
     Args:
-        text: The heading text content.
+        text: The heading text content (may contain inline HTML).
 
     Returns:
         A URL-safe slug string.
     """
+    # Strip any inline HTML so it does not pollute the slug
+    text = re.sub(r"<[^>]+>", "", text)
+    # Decode HTML entities so &amp; becomes & before slugification
+    text = html_mod.unescape(text)
     text = text.lower()
     text = unicodedata.normalize("NFD", text)
     text = "".join(ch for ch in text if not unicodedata.combining(ch))
@@ -894,7 +900,12 @@ _markdown_renderer = mistune.create_markdown(
 def _convert_wikilinks(content: str, current_vault: str) -> str:
     """Convert ``[[wikilinks]]`` and ``[[target|display]]`` to clickable HTML.
 
-    Resolved links get a ``data-vault`` / ``data-path`` attribute pair.
+    Supports:
+    - Internal file links: ``[[My Note]]`` / ``[[My Note|display]]``
+    - Same-document anchors: ``[[#Heading]]`` / ``[[#Heading|display]]``
+
+    Resolved file links get a ``data-vault`` / ``data-path`` attribute pair.
+    Anchor links target the slugified heading ID in the current document.
     Unresolved links are rendered as ``<span class="wikilink-missing">``.
 
     Args:
@@ -907,6 +918,14 @@ def _convert_wikilinks(content: str, current_vault: str) -> str:
     def _replace(match):
         target = match.group(1).strip()
         display = match.group(2).strip() if match.group(2) else target
+
+        # Same-document anchor link: [[#Heading|display]]
+        if target.startswith("#"):
+            anchor_text = target[1:].strip()
+            anchor_slug = _heading_slugify(anchor_text)
+            link_display = display if display != target else anchor_text
+            return f'<a class="wikilink-anchor" href="#{anchor_slug}">{link_display}</a>'
+
         found = find_file_in_index(target, current_vault)
         if found:
             return (