feat: sidebar arborescence Gitea + tab user repos avec vrai username

1. Tab user repos: fetch username via /auth/user → affiche 'bruno' au lieu de 'Personal'
2. Sidebar: ws_cookie='gitea:owner:repo' → _sidebar_data() fetch le tree depuis Gitea API
3. base.html: data-gitea-path/type/sha sur les items workspace pour les projets Gitea
4. gitea_workspace.html: refonte sans tree panel → navigation via sidebar
   - Clic fichier → ouvre dans le contenu (lecture + edit + commit)
   - Clic dossier → lazy-load les enfants dans le sidebar
5. openGitea(): set cookie flowdeck_workspace avant navigation

app/routers/dashboard.py

@@ -69,7 +69,41 @@ def _sidebar_data(request: Request, repos: list[dict]) -> dict:
     ws_cookie = request.cookies.get("flowdeck_workspace", "")
     active_ws_name = "Workspace"
     workspace_pages = []
-    if ws_cookie:
+    gitea_workspace = False
+
+    if ws_cookie and ws_cookie.startswith("gitea:"):
+        # Gitea workspace: fetch repo tree for sidebar
+        parts = ws_cookie.split(":", 2)
+        if len(parts) >= 3:
+            gitea_owner = parts[1]
+            gitea_repo = parts[2]
+            active_ws_name = f"{gitea_owner}/{gitea_repo}"
+            gitea_workspace = True
+            # Fetch root tree from Gitea API (use admin token as fallback)
+            try:
+                from app.services.gitea_client import get_user_gitea_client, GiteaClient
+                gitea = get_user_gitea_client(request) or GiteaClient()
+                import asyncio
+                tree_items = asyncio.run(gitea.get_repo_contents(gitea_owner, gitea_repo))
+                for item in tree_items:
+                    is_folder = item.get("type") == "dir"
+                    workspace_pages.append({
+                        "id": item.get("path", ""),
+                        "name": item.get("name", ""),
+                        "icon": "📁" if is_folder else "📄",
+                        "url": f"javascript:void(0)",
+                        "active": False,
+                        "indent": 0,
+                        "depth": 0,
+                        "has_children": is_folder,
+                        "children": [],
+                        "_gitea_path": item.get("path", ""),
+                        "_gitea_type": "folder" if is_folder else "file",
+                        "_gitea_sha": item.get("sha", ""),
+                    })
+            except Exception:
+                pass
+    elif ws_cookie:
         workspace_pages = _load_workspace_pages(ws_cookie)
         try:
             with get_conn() as conn:
@@ -83,6 +117,7 @@ def _sidebar_data(request: Request, repos: list[dict]) -> dict:
         "workspace_name": ws, "workspace_initial": initial,
         "active_ws_name": active_ws_name,
         "workspace_pages": workspace_pages,
+        "gitea_workspace": gitea_workspace,
         "current_page": "Dashboard", "last_edited": "now",
         "recent_pages": recent_pages,
         "private_pages": [],