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

.streamlit/config.toml

@@ -1,7 +1,7 @@
 [theme]
-base = "light"
-primaryColor = "#2E75B6"
-backgroundColor = "#ffffff"
-secondaryBackgroundColor = "#f0f2f6"
-textColor = "#1a1a1a"
+base = "dark"
+primaryColor = "#7c6af7"
+backgroundColor = "#0e1117"
+secondaryBackgroundColor = "#1a1f2e"
+textColor = "#fafafa"
 font = "sans serif"