feat(v4.0): Library tabs + Sidebar OAuth badge + Sharing routes

app/routers/library.py: /api/library/recents|favorites|shared|published|private|workspace
app/routers/sharing.py: /api/pages/{id}/share|publish + page_shares
app/templates/base.html: OAuth badge 🦎/🐙, '→ Library' buttons
app/templates/library.html: page avec tabs + filtres source
app/routers/dashboard.py: auth_method + github_linked dans context
tests/test_app.py: tests library + sharing + recents

app/routers/board.py

@@ -303,13 +303,37 @@ def _sidebar_data(request: Request, owner: str = "", repo: str = "") -> dict:
             "children": [],
         })
 
+    # Auth method & OAuth badge data
+    auth_method = "local"
+    gitea_linked = False
+    github_linked = False
+    if user and user.get("id"):
+        try:
+            with get_conn() as conn:
+                am_row = conn.execute("SELECT auth_method FROM users WHERE id=?", (user["id"],)).fetchone()
+                if am_row and am_row["auth_method"]:
+                    auth_method = am_row["auth_method"]
+                tokens = conn.execute(
+                    "SELECT provider FROM user_oauth_tokens WHERE user_id=?", (user["id"],)
+                ).fetchall()
+                for t in tokens:
+                    if t["provider"] == "gitea":
+                        gitea_linked = True
+                    elif t["provider"] == "github":
+                        github_linked = True
+        except Exception:
+            pass
+
     return {"workspace_name": ws_name, "workspace_initial": ws_name[0].upper() if ws_name else "B",
             "active_ws_name": active_ws_name,
             "workspace_pages": _load_workspace_pages(ws_cookie),
             "current_page": repo or "Dashboard", "last_edited": "now",
             "recent_pages": recent, "private_pages": private_items,
             "favorite_pages": favorites, "shared_pages": shared_pages,
-            "user": user, "workspace_key": ws_key}
+            "user": user, "workspace_key": ws_key,
+            "auth_method": auth_method,
+            "gitea_linked": gitea_linked,
+            "github_linked": github_linked}
 
 
 def _extract_ai_keywords(owner: str, repo: str, labels: list[dict], body: str = ""):