feat: completude de l'editeur Excel - mise en forme, sortie, concurrence, cache, outils IA #156

L'editeur lisait les styles mais ne les ecrivait pas, exportait la feuille
entiere et laissait le dernier-ecrivain gagner entre processus.

- A8 : bouton Mise en forme (gras/italique/souligne, alignements, couleurs via
  selecteur natif, formats de nombre, fusion, volets figes, largeur/hauteur) et
  nouvelle route PUT .../xlsx/style (verrou, backup, swap atomique, garde de
  perte, If-Match) ; A9 : decision "pas de moteur de formule" annoncee dans
  l'UI ; A10 : undo/redo unifie, piles par fichier conservees au re-rendu
- A11 : export de la selection + Markdown/HTML/impression et recherche sur
  toutes les feuilles ; A12 : concurrence optimiste (If-Match -> 409 reparable,
  retry qui relit) ; A13 : cache des metadonnees par (chemin, mtime, taille)
- A14 : outils IA .xlsm/.csv + search_workbook, analyze_range,
  edit_xlsx_structure
- tests : test_xlsx_styles.py (17), test_spreadsheet_tools.py (34),
  TestOptimisticConcurrency/TestMetaCache, JSDOM xlsx-viewer 107/107

backend/routers/files_read.py

@@ -42,6 +42,7 @@ from backend.schemas import (
     XlsxSheetWindowResponse,
 )
 from backend.services.files import read_raw_file
+from backend.services.mutations import file_revision
 from backend.services.paths import resolve_safe_path
 from backend.services.vaults import browse_directory, get_vault_root
 
@@ -226,7 +227,7 @@ def api_file_xlsx_dashboard(
 )
 def api_file_xlsx_sheet(
     vault_name: str,
-    path: str = Query(..., description="Relative path to the .xlsx file"),
+    path: str = Query(..., description="Relative path to the .xlsx/.xlsm file"),
     sheet: str = Query(..., description="Sheet name (as shown in the viewer tab)"),
     offset: int = Query(0, ge=0, description="0-based index of the first row to return"),
     limit: int = Query(
@@ -234,7 +235,7 @@ def api_file_xlsx_sheet(
     ),
     current_user=Depends(require_auth),
 ):
-    """Return a window of rows of one sheet of an .xlsx workbook (#153 A9).
+    """Return a window of rows of one sheet of an .xlsx/.xlsm workbook (#153 A9).
 
     Backs the viewer's lazy loading: instead of every sheet in a single JSON
     payload, the client asks for the block it is about to display. The row
@@ -258,7 +259,7 @@ def api_file_xlsx_sheet(
 
     Raises:
         HTTPException: 403 (vault access), 404 (vault, file or sheet unknown),
-            415 (not an .xlsx file), 500 (unreadable workbook).
+            415 (not an .xlsx/.xlsm file), 500 (unreadable workbook).
     """
     if not check_vault_access(vault_name, current_user):
         raise HTTPException(status_code=403, detail=f"Accès refusé à la vault '{vault_name}'")
@@ -269,8 +270,12 @@ def api_file_xlsx_sheet(
     file_path = resolve_safe_path(Path(vault_data["path"]), path)
     if not file_path.is_file():
         raise HTTPException(status_code=404, detail=f"File not found: {path}")
-    if file_path.suffix.lower() != ".xlsx":
-        raise HTTPException(status_code=415, detail="Le fichier n'est pas un classeur .xlsx")
+    # BUG-097 — a .xlsm rides the same editable viewer (and its lazy loading),
+    # so its row windows must be servable too; other formats stay refused.
+    if file_path.suffix.lower() not in (".xlsx", ".xlsm"):
+        raise HTTPException(
+            status_code=415, detail="Le fichier n'est pas un classeur .xlsx/.xlsm"
+        )
 
     # Import tardif : openpyxl n'est chargé que si un .xlsx est réellement demandé.
     from backend.xlsx_reader import read_sheet_window
@@ -368,6 +373,10 @@ async def api_file(vault_name: str, path: str = Query(..., description="Relative
                 "is_markdown": False,
                 "is_xlsx": True,
                 "xlsx_sheets": sheets,
+                # #156-A12 — optimistic-concurrency token: the viewer sends it
+                # back as `if_match` so another writer cannot be overwritten in
+                # silence (409 `conflict` instead).
+                "xlsx_revision": file_revision(file_path),
                 # #153 A1 — parts a save would drop; the viewer warns and asks
                 # for an explicit confirmation before forcing the write.
                 "xlsx_lossy_features": inspect_workbook(file_path),
@@ -507,6 +516,7 @@ async def api_file(vault_name: str, path: str = Query(..., description="Relative
                 "is_markdown": False,
                 "is_xlsx": True,
                 "xlsx_sheets": sheets,
+                "xlsx_revision": file_revision(file_path),
                 # Macros are NOT lossy for .xlsm: keep_vba re-serializes them
                 # (an empty LOSSY probe is what makes the save gate pass).
                 "xlsx_lossy_features": [],
@@ -554,6 +564,8 @@ async def api_file(vault_name: str, path: str = Query(..., description="Relative
             "title": file_path.name, "tags": [], "frontmatter": {},
             "html": html, "raw_length": len(raw), "extension": ext,
             "is_markdown": False, "is_csv": True,
+            # #156-A12 — same stale-write guard as the workbooks.
+            "xlsx_revision": file_revision(file_path),
         }
 
     # === JSON: syntax-highlighted display ===