feat(viz): price-action sparkline in MarketDataPanel

The DayTrader Market Data panel rendered candles as a number table only. Add a
price sparkline from the candle closes (green up / red down) — the Vision
"Price Action / Sparklines" MVP feature. Tested via direct render.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: GroverChorizo

tests/widgets/test_market_panel_sparkline.py

@@ -0,0 +1,28 @@
+"""MarketDataPanel renders a price-action sparkline from candle closes."""
+
+from __future__ import annotations
+
+from rich.console import Console
+
+from tui.widgets.market_data_panel import MarketDataPanel
+
+
+def _text(renderable) -> str:
+    console = Console(record=True, width=120)
+    console.print(renderable)
+    return console.export_text()
+
+
+def test_market_panel_renders_price_sparkline():
+    panel = MarketDataPanel()
+    closes = [100, 102, 101, 105, 108, 107, 110, 109, 113]
+    panel.render_data(
+        {
+            "selected_coin": "BTC",
+            "candles_1h": [
+                {"timestamp_ms": i, "close": v} for i, v in enumerate(closes)
+            ],
+        }
+    )
+    out = _text(panel.renderable)
+    assert any(ch in out for ch in "▁▂▃▄▅▆▇█")  # sparkline glyphs present

tui/widgets/market_data_panel.py

@@ -14,6 +14,7 @@
     muted_line,
     panel_header,
 )
+from tui.render.sparkline import sparkline
 from .panel_base import PanelBase
 
 
@@ -211,6 +212,18 @@ def _render_candles(
         if not isinstance(candles, list) or not candles:
             lines.append(muted_line("No candle data.", self.palette))
             return
+        closes = [
+            c.get("close")
+            for c in candles
+            if isinstance(c, dict) and c.get("close") is not None
+        ]
+        if len(closes) >= 2:
+            color = (
+                self.palette.accent.green
+                if closes[-1] >= closes[0]
+                else self.palette.accent.red
+            )
+            lines.append((f"  {sparkline(closes, width=40)}", color))
         lines.append(
             ("Time | Open | High | Low | Close | Vol", self.palette.accent.purple)
         )