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/api/v1/auth.py

@@ -61,10 +61,14 @@ async def login(
     access_token = create_access_token(data={"sub": user.id})
     refresh_token = create_refresh_token(data={"sub": user.id})
 
+    expires_in = None
+    if settings.ACCESS_TOKEN_EXPIRE_MINUTES > 0:
+        expires_in = settings.ACCESS_TOKEN_EXPIRE_MINUTES * 60
+
     return {
         "access_token": access_token,
         "token_type": "bearer",
-        "expires_in": settings.ACCESS_TOKEN_EXPIRE_MINUTES * 60,
+        "expires_in": expires_in,
         "user": {
             "id": user.id,
             "username": user.username,
@@ -79,10 +83,14 @@ async def refresh_token(
 ):
     access_token = create_access_token(data={"sub": current_user.id})
 
+    expires_in = None
+    if settings.ACCESS_TOKEN_EXPIRE_MINUTES > 0:
+        expires_in = settings.ACCESS_TOKEN_EXPIRE_MINUTES * 60
+
     return {
         "access_token": access_token,
         "token_type": "bearer",
-        "expires_in": settings.ACCESS_TOKEN_EXPIRE_MINUTES * 60,
+        "expires_in": expires_in,
         "user": {
             "id": current_user.id,
             "username": current_user.username,