Add tools/planet.py: rank planets for a resource with real founding cost

Ranks every planet with a given extraction factor using FIO's bulk
planet data, pricing founding cost straight from FIO's own
BuildRequirements (real environment-extras materials for that specific
planet, not guessed temperature/pressure thresholds - PRUNplanner's own
calculations don't model those either). Takes --from an existing base
to report jump distance via tools/route.py, since pure-factor ranking
alone is misleading: the best-factor planets found for FEO were all
500-2600+ ly away, confirming Vulcan (merely decent factor, same system
as Deimos) was still the right practical pick.

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

puga/planet.py

@@ -0,0 +1,27 @@
+"""Rank planets by extraction factor for a resource, with founding cost (environment extras
+from FIO's own BuildRequirements - authoritative, not guessed from temperature/pressure
+thresholds, which PRUNplanner's own calculations don't model either)."""
+from . import fio
+
+
+def candidates(resource_ticker: str, min_factor: float = 0.0):
+    """All planets with this resource, sorted by factor descending. Each: PlanetNaturalId,
+    PlanetName, factor, resource_type, plus the raw planet record (temperature/pressure/
+    gravity/fertility/faction/BuildRequirements/SystemId etc)."""
+    mats = {m["Ticker"]: m["MaterialId"] for m in fio.materials()}
+    mid = mats.get(resource_ticker.upper())
+    if not mid:
+        raise ValueError(f"unknown material ticker {resource_ticker!r}")
+    out = []
+    for p in fio.planets_full():
+        for r in p.get("Resources", []):
+            if r["MaterialId"] == mid and r["Factor"] >= min_factor:
+                out.append({
+                    "natural_id": p["PlanetNaturalId"], "name": p["PlanetName"],
+                    "factor": r["Factor"], "resource_type": r["ResourceType"],
+                    "temperature": p["Temperature"], "pressure": p["Pressure"], "gravity": p["Gravity"],
+                    "fertility": p["Fertility"], "faction": p.get("FactionCode"),
+                    "system_id": p["SystemId"], "build_requirements": p.get("BuildRequirements", []),
+                })
+    out.sort(key=lambda x: -x["factor"])
+    return out