fix: import json, style maybe cells, fix Enter key in admin date form

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

app.py

@@ -1,3 +1,4 @@
+import json
 from datetime import datetime
 from flask import Flask, render_template, request, jsonify
 from flask_sqlalchemy import SQLAlchemy

templates/admin.html

@@ -462,7 +462,7 @@
 
         // Allow Enter key on start-date and weeks
         document.getElementById('start-date').addEventListener('keydown', e => {
-            if (e.key === 'Enter') previewDates();
+            if (e.key === 'Enter') createSeason();
         });
 
         init();

templates/index.html

@@ -24,6 +24,7 @@
         }
         .yes { background: #948979; font-weight: bold; color: #222831; }
         .no { background: #393E46; color: #948979; font-weight: bold; }
+        .maybe { background: #4a3a00; font-weight: bold; color: #DFD0B8; }
         input[type="text"] {
             width: 90%;
             padding: 0.2em;