feat: trade analysis overhaul — editing, grouping, comparison views

Trade Analysis:
- Add editable raw trade log with # index and Group column
- Group column merges multiple entries into one position on Update
- Reset button clears edited version back to original upload
- View selector: Original / Edited / Both — appears after first Update
- Both mode: stats show with coloured delta arrows vs edited version
- Both mode: equity, drawdown and daily P&L charts overlay both versions
- Both mode: strategy comparison table shows inline delta values
- Position Summary expander above monthly table — all positions listed
  (grouped with entry count, individual as single rows) sorted by open time
- Download exports edited version when available, original otherwise
- Trade # multiselect filter to show specific trades
- All charts and tables (DOW, hour, monthly) respect view selection
- Fix: Group column positioned second after # index
- Fix: DataFrame truth value error in download button
- Fix: Both mode now uses edited df for DOW/hour/monthly charts

mt5_parser:
- Add trading_days and trades_per_day to calc_stats
- Add ISO datetime format fallback for CSV imports
- Fix missing comment column KeyError in _enrich
- Fix NaT in date filter when open_time has null values

mt5_parser.py

@@ -350,8 +350,13 @@ def calc_stats(df):
     longs  = df[df['type'] == 'buy']
     shorts = df[df['type'] == 'sell']
 
+    trading_days   = df['open_time'].dt.date.nunique() if 'open_time' in df.columns else 0
+    trades_per_day = round(total / trading_days, 2) if trading_days > 0 else 0
+
     return {
         'total_trades'      : total,
+        'trading_days'      : trading_days,
+        'trades_per_day'    : trades_per_day,
         'win_rate'          : win_rate,
         'net_profit'        : net_profit,
         'gross_profit'      : gross_profit,