feat(WP-03): add evolution track seed data

JSON definitions and idempotent seed function for the 3 universal
evolution tracks (Batter, Starting Pitcher, Relief Pitcher) with
locked threshold values.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/seed/evolution_tracks.json

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+[
+  {
+    "name": "Batter Track",
+    "card_type": "batter",
+    "formula": "pa + tb * 2",
+    "t1_threshold": 37,
+    "t2_threshold": 149,
+    "t3_threshold": 448,
+    "t4_threshold": 896
+  },
+  {
+    "name": "Starting Pitcher Track",
+    "card_type": "sp",
+    "formula": "ip + k",
+    "t1_threshold": 10,
+    "t2_threshold": 40,
+    "t3_threshold": 120,
+    "t4_threshold": 240
+  },
+  {
+    "name": "Relief Pitcher Track",
+    "card_type": "rp",
+    "formula": "ip + k",
+    "t1_threshold": 3,
+    "t2_threshold": 12,
+    "t3_threshold": 35,
+    "t4_threshold": 70
+  }
+]

app/seed/evolution_tracks.py

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+"""Seed script for EvolutionTrack records.
+
+Loads track definitions from evolution_tracks.json and upserts them into the
+database using get_or_create keyed on name. Existing tracks have their
+thresholds and formula updated to match the JSON in case values have changed.
+
+Can be run standalone:
+    python -m app.seed.evolution_tracks
+"""
+
+import json
+from pathlib import Path
+
+from app.db_engine import EvolutionTrack
+
+_JSON_PATH = Path(__file__).parent / "evolution_tracks.json"
+
+
+def seed_evolution_tracks() -> list[EvolutionTrack]:
+    """Upsert evolution tracks from JSON seed data.
+
+    Returns a list of EvolutionTrack instances that were created or updated.
+    """
+    raw = _JSON_PATH.read_text(encoding="utf-8")
+    track_defs = json.loads(raw)
+
+    results: list[EvolutionTrack] = []
+
+    for defn in track_defs:
+        track, created = EvolutionTrack.get_or_create(
+            name=defn["name"],
+            defaults={
+                "card_type": defn["card_type"],
+                "formula": defn["formula"],
+                "t1_threshold": defn["t1_threshold"],
+                "t2_threshold": defn["t2_threshold"],
+                "t3_threshold": defn["t3_threshold"],
+                "t4_threshold": defn["t4_threshold"],
+            },
+        )
+
+        if not created:
+            # Update mutable fields in case the JSON values changed.
+            track.card_type = defn["card_type"]
+            track.formula = defn["formula"]
+            track.t1_threshold = defn["t1_threshold"]
+            track.t2_threshold = defn["t2_threshold"]
+            track.t3_threshold = defn["t3_threshold"]
+            track.t4_threshold = defn["t4_threshold"]
+            track.save()
+
+        action = "created" if created else "updated"
+        print(f"  [{action}] {track.name} (card_type={track.card_type})")
+        results.append(track)
+
+    return results
+
+
+if __name__ == "__main__":
+    print("Seeding evolution tracks...")
+    tracks = seed_evolution_tracks()
+    print(f"Done. {len(tracks)} track(s) processed.")