feat(excalidraw): support complet des fichiers .excalidraw (#78)

- Backend: ajout .excalidraw dans SUPPORTED_EXTENSIONS + squelette JSON creation
- Backend: détection is_excalidraw dans api_file() + FileContentResponse
- Frontend: icône pen-tool dans EXT_ICONS
- Frontend: ajout dans la modale de création (ui.js)
- Frontend: excalidraw-editor.html (iframe autonome, React+Excalidraw via esm.sh)
- Frontend: excalidraw-viewer.js (postMessage, auto-save 2s, thème)
- Frontend: dispatch dans viewer.js (renderFile)
- Tests: 6 tests (détection, création squelette, fallback, tree, roundtrip)
- 359/359 tests passent

backend/indexer.py

@@ -63,6 +63,7 @@ SUPPORTED_EXTENSIONS = {
     ".java", ".c", ".cpp", ".h", ".hpp", ".cs", ".go", ".rs", ".rb",
     ".php", ".sql", ".r", ".m", ".swift", ".kt",
     ".dockerfile", ".makefile", ".cmake",
+    ".excalidraw",
 }
 
 

backend/main.py

@@ -118,6 +118,15 @@ class FileContentResponse(BaseModel):
     is_markdown: bool = Field(description="Whether the file is markdown")
     unsupported: bool | None = Field(default=False, description="True for binary/unsupported files")
     size_bytes: int | None = Field(default=None, description="File size in bytes (for unsupported files)")
+    is_pdf: bool | None = Field(default=None, description="True for PDF files")
+    is_image: bool | None = Field(default=None, description="True for image files")
+    is_csv: bool | None = Field(default=None, description="True for CSV files")
+    is_json: bool | None = Field(default=None, description="True for JSON files")
+    is_excalidraw: bool | None = Field(default=None, description="True for Excalidraw diagram files")
+    excalidraw_data: dict[str, Any] | None = Field(default=None, description="Excalidraw diagram data (elements, appState, files)")
+    pdf_metadata: dict[str, Any] | None = Field(default=None, description="PDF metadata")
+    pdf_toc: list[dict[str, Any]] | None = Field(default=None, description="PDF table of contents")
+    image_mime: str | None = Field(default=None, description="MIME type for image files")
 
 
 class FileRawResponse(BaseModel):
@@ -1793,8 +1802,13 @@ async def api_file_create(
         # Create parent directories if needed
         file_path.parent.mkdir(parents=True, exist_ok=True)
         
+        # For .excalidraw files, inject skeleton JSON if content is empty
+        content = body.content
+        if ext == ".excalidraw" and not content.strip():
+            content = '{"type":"excalidraw","version":2,"elements":[],"appState":{"viewBackgroundColor":"#ffffff"},"files":{}}'
+        
         # Create file with initial content
-        file_path.write_text(body.content, encoding="utf-8")
+        file_path.write_text(content, encoding="utf-8")
         logger.info(f"File created: {vault_name}/{body.path}")
         
         # Update index
@@ -2489,6 +2503,35 @@ async def api_file(vault_name: str, path: str = Query(..., description="Relative
             "is_markdown": False, "is_json": True,
         }
 
+    # === Excalidraw: diagram editor ===
+    if ext == ".excalidraw":
+        import json as json_mod
+        try:
+            parsed = json_mod.loads(raw)
+        except json_mod.JSONDecodeError:
+            parsed = None
+        if parsed and parsed.get("type") == "excalidraw":
+            return {
+                "vault": vault_name,
+                "path": path,
+                "title": parsed.get("appState", {}).get("name") or file_path.name,
+                "tags": [],
+                "frontmatter": {},
+                "html": "",
+                "raw_length": len(raw),
+                "extension": ext,
+                "is_markdown": False,
+                "is_excalidraw": True,
+                "excalidraw_data": {
+                    "elements": parsed.get("elements", []),
+                    "appState": parsed.get("appState", {}),
+                    "files": parsed.get("files", {}),
+                },
+            }
+        else:
+            # Not a valid Excalidraw file — fall through to text viewer
+            pass
+
     # === Plain text / other readable files ===
     TEXT_EXTENSIONS = {".txt", ".log", ".yml", ".yaml", ".toml", ".ini", ".cfg",
                        ".sh", ".bash", ".py", ".js", ".ts", ".html", ".css",