Function localSiderealTime

localSiderealTime(gmst: number, longitude: number): number
Calculate Local Sidereal Time from GMST and longitude

LST is simply GMST adjusted for the observer's longitude. Longitude is positive East, negative West (standard astronomical convention).

Formula: LST = GMST + longitude
Parameters
- gmst: number
  Greenwich Mean Sidereal Time in degrees (0-360)
- longitude: number
  Observer's longitude in degrees (positive East, negative West)
Returns number
Local Sidereal Time in degrees (0-360)
Example
```
// Greenwich (longitude = 0)
localSiderealTime(280, 0)  // Returns: 280 (LST = GMST)
```
Example
```
// New York (longitude ≈ -74°)
localSiderealTime(280, -74)  // Returns: 206
```
Example
```
// Tokyo (longitude ≈ 139.7°)
localSiderealTime(280, 139.7)  // Returns: 59.7
```
- Defined in time/local-sidereal-time.ts:36