v5.4.1 Partage : correctif permissions + autocomplete membres (inclut v5.4.0 Interactions de bloc)

- Fix "Invalid permission" : le client envoyait editor/commenter/viewer alors que
  l'API attend view/comment/edit (invitePermission -> 'edit', menu participants aligné)
- PUT /api/pages/{page_id}/share/{share_id} : mise à jour de permission persistée
- Autocomplete des membres existants dans le champ d'invitation (search users + debounce,
  navigation clavier, envoi user_id pour lier le partage au compte)
- Upsert anti-doublon dans le partage + trim email backend
- 12 tests tests/test_sharing.py ; suite 319 verte (+3 PDF pre-existants)

Sans oublier v5.4.0 (non publie jusque-la) :
- Undo/Redo (Ctrl+Z/Ctrl+Shift+Z/Ctrl+Y), duplicate (Ctrl+D), menu de bloc (turn
  into, couleurs, lien #fdblk-, move to, delete), drag&drop multi-selection,
  slash "Actions", en-tetes de tableau (has_header/first_col_header) + exports,
  sync realtime immédiat apres mutation ; 9 tests test_block_interactions.py

app/services/export.py

@@ -264,24 +264,28 @@ def _table_to_markdown(b: dict) -> str:
     align = b.get("align") or []
     width = max(len(r) for r in rows)
     align = (align + ["left"] * width)[:width]
+    has_header = b.get("has_header", True)
     out: list[str] = []
 
     def rowline(r):
         cells = list(r) + [""] * (width - len(r))
         return "| " + " | ".join(cells) + " |"
 
-    for ri, r in enumerate(rows):
-        out.append(rowline(r))
-        if b.get("has_header") and ri == 0:
-            seps = []
-            for a in align:
-                if a == "center":
-                    seps.append(":---:")
-                elif a == "right":
-                    seps.append("---:")
-                else:
-                    seps.append(":---")
-            out.append("| " + " | ".join(seps) + " |")
+    start = 0
+    if has_header:
+        out.append(rowline(rows[0]))
+        seps = []
+        for a in align:
+            if a == "center":
+                seps.append(":---:")
+            elif a == "right":
+                seps.append("---:")
+            else:
+                seps.append(":---")
+        out.append("| " + " | ".join(seps) + " |")
+        start = 1
+    for ri in range(start, len(rows)):
+        out.append(rowline(rows[ri]))
     return "\n".join(out)
 
 
@@ -297,16 +301,30 @@ def _table_to_html(b: dict) -> str:
         style = f' style="text-align:{a};"' if a and a != "left" else ""
         return f"<{tag}{style}>{_text(text)}</{tag}>"
 
-    def row_html(r, tag_default):
-        cells = list(r) + [""] * (width - len(r))
-        return "<tr>" + "".join(cell_html(tag_default, c, align[ci]) for ci, c in enumerate(cells)) + "</tr>"
-
-    header_rows = 1 if b.get("has_header") else 0
+    has_header = b.get("has_header", True)
+    first_col = b.get("first_col_header", False)
+    header_rows = 1 if has_header else 0
     head = ""
     if header_rows:
-        head = "<thead>" + "".join(row_html(r, "th") for r in rows[:header_rows]) + "</thead>"
+        head_rows = []
+        hr = rows[0]
+        cells = list(hr) + [""] * (width - len(hr))
+        head_cells = []
+        for ci, c in enumerate(cells):
+            tag = "th" if first_col and ci == 0 else "th"
+            head_cells.append(cell_html(tag, c, align[ci]))
+        head_rows.append("<tr>" + "".join(head_cells) + "</tr>")
+        head = "<thead>" + "".join(head_rows) + "</thead>"
     tbody_rows = rows[header_rows:]
-    body = "<tbody>" + "".join(row_html(r, "td") for r in tbody_rows) + "</tbody>"
+    body_rows = []
+    for r in tbody_rows:
+        cells = list(r) + [""] * (width - len(r))
+        row_cells = []
+        for ci, c in enumerate(cells):
+            tag = "th" if first_col and ci == 0 else "td"
+            row_cells.append(cell_html(tag, c, align[ci]))
+        body_rows.append("<tr>" + "".join(row_cells) + "</tr>")
+    body = "<tbody>" + "".join(body_rows) + "</tbody>"
     return f'<table class="ftable">{head}{body}</table>'