feat(backend): Add cable graph service and data collectors

## Changelog

### New Features

#### Cable Graph Service
- Add cable_graph.py for finding shortest path between landing points
- Implement haversine distance calculation for great circle distances
- Support for dateline crossing (longitude normalization)
- NetworkX-based graph for optimal path finding

#### Data Collectors
- Add ArcGISCableCollector for fetching submarine cable data from ArcGIS GeoJSON API
- Add FAOLandingPointCollector for fetching landing point data from FAO CSV API

### Backend Changes

#### API Updates
- auth.py: Update authentication logic
- datasources.py: Add datasource endpoints and management
- visualization.py: Add visualization API endpoints
- config.py: Update configuration settings
- security.py: Improve security settings

#### Models & Schemas
- task.py: Update task model with new fields
- token.py: Update token schema

#### Services
- collectors/base.py: Improve base collector with better error handling
- collectors/__init__.py: Register new collectors
- scheduler.py: Update scheduler logic
- tasks/scheduler.py: Add task scheduling

### Frontend Changes
- AppLayout.tsx: Improve layout component
- index.css: Add global styles
- DataSources.tsx: Enhance data sources management page
- vite.config.ts: Add Vite configuration for earth module

backend/app/services/collectors/arcgis_cables.py

@@ -0,0 +1,84 @@
+"""ArcGIS Submarine Cables Collector
+
+Collects submarine cable data from ArcGIS GeoJSON API.
+"""
+
+import json
+from typing import Dict, Any, List
+from datetime import datetime
+import httpx
+
+from app.services.collectors.base import BaseCollector
+
+
+class ArcGISCableCollector(BaseCollector):
+    name = "arcgis_cables"
+    priority = "P1"
+    module = "L2"
+    frequency_hours = 168
+    data_type = "submarine_cable"
+
+    base_url = "https://services.arcgis.com/6DIQcwlPy8knb6sg/arcgis/rest/services/SubmarineCables/FeatureServer/2/query"
+
+    async def fetch(self) -> List[Dict[str, Any]]:
+        params = {"where": "1=1", "outFields": "*", "returnGeometry": "true", "f": "geojson"}
+
+        async with httpx.AsyncClient(timeout=60.0) as client:
+            response = await client.get(self.base_url, params=params)
+            response.raise_for_status()
+            return self.parse_response(response.json())
+
+    def parse_response(self, data: Dict[str, Any]) -> List[Dict[str, Any]]:
+        result = []
+
+        features = data.get("features", [])
+        for feature in features:
+            props = feature.get("properties", {})
+            geometry = feature.get("geometry", {})
+
+            route_coordinates = []
+            if geometry.get("type") == "MultiLineString":
+                coords = geometry.get("coordinates", [])
+                for line in coords:
+                    line_coords = []
+                    for point in line:
+                        if len(point) >= 2:
+                            line_coords.append(point)
+                    if line_coords:
+                        route_coordinates.append(line_coords)
+            elif geometry.get("type") == "LineString":
+                coords = geometry.get("coordinates", [])
+                line_coords = []
+                for point in coords:
+                    if len(point) >= 2:
+                        line_coords.append(point)
+                if line_coords:
+                    route_coordinates.append(line_coords)
+
+            try:
+                entry = {
+                    "source_id": f"arcgis_cable_{props.get('cable_id', props.get('OBJECTID', ''))}",
+                    "name": props.get("Name", "Unknown"),
+                    "country": "",
+                    "city": "",
+                    "latitude": "",
+                    "longitude": "",
+                    "value": str(props.get("length", "")).replace(",", ""),
+                    "unit": "km",
+                    "metadata": {
+                        "cable_id": props.get("cable_id"),
+                        "owners": props.get("owners"),
+                        "rfs": props.get("rfs"),
+                        "status": "active",
+                        "year": props.get("year"),
+                        "url": props.get("url"),
+                        "color": props.get("color"),
+                        "route_coordinates": route_coordinates,
+                    },
+                    "reference_date": datetime.utcnow().strftime("%Y-%m-%d"),
+                }
+                result.append(entry)
+            except (ValueError, TypeError, KeyError):
+                continue
+
+        return result