Closes #69

- Create migrations/2026-03-12_add_evolution_tables.sql: idempotent
  PostgreSQL migration (BEGIN/COMMIT, all IF NOT EXISTS) that creates
  player_season_stats, evolution_track, evolution_card_state,
  evolution_tier_boost, and evolution_cosmetic tables; adds card.variant
  (INTEGER NULL DEFAULT NULL), battingcard.image_url (VARCHAR(500) NULL),
  and pitchingcard.image_url (VARCHAR(500) NULL).
- Add tests/test_evolution_migration.py: 16 unit tests validate SQL file
  structure (tables, columns, indexes, FK references, idempotency); 6
  integration tests annotated for PostgreSQL execution when POSTGRES_HOST
  is set.
- Add tests/__init__.py and tests/conftest.py (shared test infrastructure
  required for import isolation).

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

@@ -0,0 +52,4 @@
+
+    -- Pitching stats
+    games_pitching  INTEGER NOT NULL DEFAULT 0,
+    outs            INTEGER NOT NULL DEFAULT 0,

@@ -0,0 +97,4 @@
+CREATE TABLE IF NOT EXISTS evolution_card_state (
+    id                  SERIAL PRIMARY KEY,
+    player_id           INTEGER NOT NULL REFERENCES player(player_id) ON DELETE CASCADE,
+    team_id             INTEGER NOT NULL REFERENCES team(id) ON DELETE CASCADE,

@@ -0,0 +133,4 @@
+-- --------------------------------------------
+-- 7. Add battingcard.image_url column
+-- --------------------------------------------
+ALTER TABLE battingcard

@@ -0,0 +34,4 @@
+        port=int(os.environ.get("POSTGRES_PORT", "5432")),
+    )
+    conn.autocommit = False
+    migration_path = os.path.join(

@@ -0,0 +26,4 @@
+BEGIN;
+
+-- --------------------------------------------
+-- 1. player_season_stats

@@ -0,0 +84,4 @@
+    id              SERIAL PRIMARY KEY,
+    name            VARCHAR(255) NOT NULL,
+    card_type       VARCHAR(255) NOT NULL UNIQUE,  -- batter / sp / rp
+    formula         VARCHAR(255) NOT NULL,

@@ -0,0 +105,4 @@
+    last_evaluated_at   TIMESTAMP NULL
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS evolution_card_state_player_team_uniq

@@ -0,0 +114,4 @@
+CREATE TABLE IF NOT EXISTS evolution_tier_boost (
+    id              SERIAL PRIMARY KEY,
+    card_state_id   INTEGER NOT NULL REFERENCES evolution_card_state(id) ON DELETE CASCADE
+);

@@ -0,0 +123,4 @@
+    id              SERIAL PRIMARY KEY,
+    card_state_id   INTEGER NOT NULL REFERENCES evolution_card_state(id) ON DELETE CASCADE
+);
+