feat: add Textual TUI with auto-refresh, leaders, playoff picture, and box score

Introduces an interactive terminal UI via the `--tui` flag backed by the
Textual framework. Scores and standings auto-refresh on a configurable
interval (default 60s, minimum 10s) using asyncio with nba_api calls
offloaded to a thread pool to keep the event loop unblocked.

New tabs:
- Scores / Standings (existing views, now live-updating)
- Leaders: top-25 by stat category, cycle with < / > keys
- Playoff Picture: conference seeding with clinch/elimination status
- Box Score: per-player live stats, load any game with keys 1–9

Refactored scores.py and standings.py to separate rendering from I/O
(get_scoreboard_table, get_east/west_standings_table), keeping the
existing static CLI path fully intact. Added -sc / -st shortcut flags.

Adds textual>=0.89.1,<7.0 dependency, build-system declaration for uv,
and package-data entry for the bundled .tcss stylesheet.

1 files changed, 50 insertions, 0 deletions

diff --git a/nba/tui/widgets.py b/nba/tui/widgets.py
new file mode 100644
index 0000000..f5e8c1d
--- /dev/null
+++ b/nba/tui/widgets.py
@@ -0,0 +1,50 @@
+"""
+Custom Textual widgets for the NBA scores TUI.
+"""
+
+from textual.reactive import reactive
+from textual.widgets import Static
+
+
+class ScoresWidget(Static):
+    """Displays the NBA scoreboard as a scrollable ANSI-formatted table."""
+
+
+class StandingsWidget(Static):
+    """Displays the NBA standings as a scrollable ANSI-formatted table."""
+
+
+class CountdownBar(Static):
+    """
+    Docked status bar that counts down to the next auto-refresh.
+
+    Maintains its own 1-second ticker and re-renders via a reactive attribute.
+    """
+
+    seconds: reactive[int] = reactive(60)
+
+    def __init__(self, interval: int, **kwargs) -> None:
+        super().__init__(**kwargs)
+        self._interval = interval
+        self.seconds = interval
+
+    def on_mount(self) -> None:
+        self.set_interval(1, self._tick)
+
+    def _tick(self) -> None:
+        if self.seconds > 0:
+            self.seconds -= 1
+
+    def watch_seconds(self, value: int) -> None:
+        if value <= 0:
+            self.update("Refreshing...")
+        else:
+            self.update(
+                f"Next refresh in {value}s  |  "
+                "\\[1-9] Box Score  |  \\[</>] Leaders Cat  |  \\[r] Refresh  |  \\[q] Quit"
+            )
+
+    def reset(self, interval: int) -> None:
+        """Reset the countdown to the given interval."""
+        self._interval = interval
+        self.seconds = interval