Match history and win rate

Every finished match goes into a small sqlite database: mode, deck, both
classes, result, turn count and who started. The result tag arrives in the
last turn of the match, so the record is written then, not when the game
object is closed (that only happens once the next match starts). The unique
key is the session directory plus the match start time, so importing old
session logs into the same database can be repeated without duplicates.

The new window (from the menu) shows the totals, the win rate by deck and by
opponent class, and the recent matches. Classes are drawn as hero portraits
cut from the card render, with the class colour as a placeholder until the
image is downloaded. Every table sorts by any column: the sort key is hidden
data, not the visible text, so dates, turn counts and results sort correctly,
and numeric columns start descending.

tools/import_history.py backfills the database from the session logs already
on disk, tests/test_history.py covers the date handling, the idempotency and
the win rate maths.

ui/theme.py

@@ -14,6 +14,9 @@ MANA_BLUE = "#1f4e8c"
 WIN = "#5fbf6a"
 LOSS = "#d0605a"
 
+# Maç sonucu: yazı yerine işaret. Hem panelde hem maç geçmişinde aynı dil.
+RESULT_MARKS = {"WON": ("✓", WIN), "LOST": ("✗", LOSS), "TIED": ("=", TEXT_DIM)}
+
 RARITY_COLORS = {
     "COMMON": "#c9cedb",
     "FREE": "#c9cedb",
@@ -131,3 +134,31 @@ QScrollBar::handle:vertical:hover {{ background: {TEXT_DIM}; }}
 QScrollBar::add-line, QScrollBar::sub-line {{ height: 0; }}
 QScrollBar::add-page, QScrollBar::sub-page {{ background: transparent; }}
 """
+
+# Maç geçmişi penceresi. Panelin aksine saydam değil: oyunun üstünde değil,
+# yanında okunan bir pencere.
+TABLE_STYLESHEET = f"""
+QWidget#history {{ background: {BACKGROUND}; }}
+QLabel#title {{ font-size: 15px; font-weight: 600; }}
+QLabel#total {{ color: {TEXT_DIM}; font-size: 12px; }}
+QTableWidget {{
+    background: transparent;
+    border: none;
+    outline: none;
+}}
+QTableWidget::item {{ padding: 2px 6px; border: none; }}
+QTableWidget::item:selected {{ background: {SURFACE_ALT}; color: {TEXT}; }}
+QHeaderView::section {{
+    background: transparent;
+    color: {TEXT_DIM};
+    border: none;
+    border-bottom: 1px solid {BORDER};
+    padding: 4px 6px;
+    font-size: 10px;
+    font-weight: 600;
+    letter-spacing: 1px;
+}}
+/* Başlıklar tıklanınca sıralıyor, imleç üstüne gelince belli olsun. */
+QHeaderView::section:hover {{ color: {TEXT}; }}
+QHeaderView::down-arrow, QHeaderView::up-arrow {{ width: 9px; height: 9px; }}
+"""