Add scan concurrency and login delay sliders

Serialised logins now sleep `login_delay` seconds between each SSH
auth to prevent AD/LDAP lockout. Both max sessions (1-10) and login
delay (0-15s) are configurable via UI sliders in the header and
passed as JSON to all scan endpoints.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -34,10 +34,12 @@ def _reschedule(interval_minutes):
     logger.info(f"Auto-scan scheduled every {interval_minutes} minutes")
 
 
-def _trigger_scan_background(dept: str = None):
+def _trigger_scan_background(dept: str = None, workers: int = 5, login_delay: int = 3):
     """Run scan in a background thread. dept=None → all switches."""
     if not scanner.scan_state["running"]:
-        t = threading.Thread(target=scanner.run_scan, kwargs={"dept": dept}, daemon=True)
+        t = threading.Thread(target=scanner.run_scan,
+                             kwargs={"dept": dept, "workers": workers, "login_delay": login_delay},
+                             daemon=True)
         t.start()
 
 
@@ -55,12 +57,20 @@ def index():
     return render_template("index.html")
 
 
+def _scan_params():
+    body = request.get_json(silent=True) or {}
+    workers = max(1, min(10, int(body.get("workers", 5))))
+    login_delay = max(0, min(30, int(body.get("login_delay", 3))))
+    return workers, login_delay
+
+
 @app.route("/api/scan", methods=["POST"])
 def api_scan():
     """Scan all active switches (no dept filter)."""
     if scanner.scan_state["running"]:
         return jsonify({"error": "Scan already running"}), 409
-    _trigger_scan_background(dept=None)
+    workers, login_delay = _scan_params()
+    _trigger_scan_background(dept=None, workers=workers, login_delay=login_delay)
     return jsonify({"status": "started", "dept": None})
 
 
@@ -74,7 +84,8 @@ def api_scan_clear():
     conn.execute("DELETE FROM links")
     conn.commit()
     conn.close()
-    _trigger_scan_background(dept=None)
+    workers, login_delay = _scan_params()
+    _trigger_scan_background(dept=None, workers=workers, login_delay=login_delay)
     return jsonify({"status": "started", "cleared": True})
 
 
@@ -83,7 +94,8 @@ def api_scan_elec():
     """Scan only ELEC department switches."""
     if scanner.scan_state["running"]:
         return jsonify({"error": "Scan already running"}), 409
-    _trigger_scan_background(dept="ELEC")
+    workers, login_delay = _scan_params()
+    _trigger_scan_background(dept="ELEC", workers=workers, login_delay=login_delay)
     return jsonify({"status": "started", "dept": "ELEC"})
 
 
@@ -92,7 +104,8 @@ def api_scan_gw():
     """Scan only GW department switches."""
     if scanner.scan_state["running"]:
         return jsonify({"error": "Scan already running"}), 409
-    _trigger_scan_background(dept="GW")
+    workers, login_delay = _scan_params()
+    _trigger_scan_background(dept="GW", workers=workers, login_delay=login_delay)
     return jsonify({"status": "started", "dept": "GW"})