Restructure into full project layout

backend/app/services/ai/constraints.py

@@ -0,0 +1,25 @@
+from app.schemas.deck import DeckConstraints
+
+
+def build_constraint_context(constraints: DeckConstraints, owned_names: list[str] | None) -> str:
+    lines = []
+
+    if constraints.prefer_owned and owned_names:
+        lines.append("- Prefer cards the user already owns (marked [OWNED] in the list below)")
+        lines.append("- Mark any recommended card the user does NOT own with [UNOWNED] suffix")
+
+    if constraints.budget_enabled and constraints.budget_amount:
+        scope = "total deck" if constraints.budget_scope == "total" else "cards to purchase"
+        lines.append(f"- Budget limit: ${constraints.budget_amount:.2f} for {scope}")
+
+    if not lines:
+        lines.append("- No special constraints — recommend the strongest cards available")
+
+    return "\n".join(lines)
+
+
+def build_owned_card_list(owned_names: list[str]) -> str:
+    if not owned_names:
+        return ""
+    card_list = "\n".join(f"- {name}" for name in sorted(owned_names))
+    return f"\nOWNED CARDS:\n{card_list}\n"