feat: add a submarine cable tool

Add find_submarine_cables over the bundled TeleGeography data: cables
passing through or landing in an area, or matching a name, with landing
points and the dataset's attribution. The local MCP server's fetch reads
the bundled data files a browser would load by URL, and nothing outside
that directory.

docs/TOOLS.md

@@ -130,6 +130,7 @@ public feeds the sources already use.
 | `get_weather_map` | `weatherMaps` | The latest NOAA radar, satellite or lightning map image over an area |
 | `get_wind` | `wind` | GFS or IFS model wind 10 m above ground at a location |
 | `get_recent_imagery` | `imagery` | The most recent clear Landsat/Sentinel-2 image of an area (VIIRS fallback) |
+| `find_submarine_cables` | `cables` | TeleGeography cables and landing points by area or name (CC BY-NC-SA 3.0) |
 | `get_regional_brief` | `regional` | What and where a location is, its weather and recent headlines |
 | `get_cyclones` | `cyclones` | Active NHC/CPHC tropical cyclones, optionally in an area |
 | `get_fire_perimeters` | `perimeters` | Mapped WFIGS wildfire perimeters in an area, largest first |