Add tools/route.py: jump-distance routing from FIO's system graph

PRUNplanner doesn't model travel, so nothing in the project could answer
"how far is planet X" until now. Builds a graph from /systemstars (698
systems, real jump connections + 3D coordinates) and runs Dijkstra
weighted by straight-line ly (what FTL fuel/time actually scale with),
reporting jump count alongside.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tools/route.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+"""Jump-distance route between two planets/systems, from FIO's system graph (not PRUNplanner,
+which doesn't model travel). Straight-line ly is the Dijkstra weight (scales with FTL fuel/time);
+jump count shown alongside.
+
+  tools/route.py ZV-759c ZV-194a      # Deimos -> Nike
+  tools/route.py Deimos "Ironforge"   # names also work
+"""
+import sys
+from pathlib import Path
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+from puga import route
+
+
+def main():
+    if len(sys.argv) != 3:
+        sys.exit("usage: tools/route.py <from planet/system> <to planet/system>")
+    a, b = sys.argv[1], sys.argv[2]
+    src = route.resolve_system(a)
+    dst = route.resolve_system(b)
+    if src == dst:
+        print(f"{a} and {b} are in the same system - 0 jumps")
+        return
+    r = route.shortest_path(src, dst)
+    if r is None:
+        print(f"no connected route found between {a} and {b}")
+        return
+    print(f"{a} -> {b}: {r['jumps']} jumps, {r['distance_ly']:.1f} ly (straight-line sum along the jump path)")
+    print("path: " + " -> ".join(r["path"]))
+
+
+if __name__ == "__main__":
+    main()