Rewrite from mongodb to sqlx (#1)

Reviewed-on: #1

migrations/001_init.sql

@@ -0,0 +1,18 @@
+CREATE TABLE characters (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    rmid INTEGER NOT NULL,
+    name TEXT NOT NULL,
+    status TEXT NOT NULL,
+    species TEXT NOT NULL,
+    type TEXT NOT NULL,
+    gender TEXT NOT NULL,
+    origin_name TEXT NOT NULL,
+    origin_url TEXT NOT NULL,
+    location_name TEXT NOT NULL,
+    location_url TEXT NOT NULL,
+    image TEXT NOT NULL,
+    episode TEXT NOT NULL, -- store as comma-separated or JSON
+    url TEXT NOT NULL,
+    created TEXT NOT NULL,
+    elo_rating REAL NOT NULL
+);