fix: improvedr pair status sharing.

- pair_devices.html template for device pairing interface
- SLMM device control lock prevents flooding nl43.
Fix:
- Polling intervals for SLMM.
- modem view now list
- device pairing much improved.
- various other tweaks through out UI.
- SLMM Scheduled downloads fixed.

backend/services/snapshot.py

@@ -151,11 +151,23 @@ def emit_status_snapshot():
         # --- Derive modem status from paired devices ---
         # Modems don't have their own check-in system, so we inherit status
         # from whatever device they're paired with (seismograph or SLM)
+        # Check both directions: modem.deployed_with_unit_id OR device.deployed_with_modem_id
         for unit_id, unit_data in units.items():
             if unit_data.get("device_type") == "modem" and not unit_data.get("retired"):
+                paired_unit_id = None
                 roster_unit = roster.get(unit_id)
+
+                # First, check if modem has deployed_with_unit_id set
                 if roster_unit and roster_unit.deployed_with_unit_id:
                     paired_unit_id = roster_unit.deployed_with_unit_id
+                else:
+                    # Fallback: check if any device has this modem in deployed_with_modem_id
+                    for other_id, other_roster in roster.items():
+                        if other_roster.deployed_with_modem_id == unit_id:
+                            paired_unit_id = other_id
+                            break
+
+                if paired_unit_id:
                     paired_unit = units.get(paired_unit_id)
                     if paired_unit:
                         # Inherit status from paired device