Add Blackjack game: rules, card rendering, game loop and tests

Implement the playable console game for gateway MIL-002.

- rules.py: deal_card, calculate_score (blackjack = 0, aces drop 11 ->
  1)
  and compare with an Outcome enum; no console I/O
- display.py: hand rendering as plain-text rank plus suit emoji (keycap
  emoji rendered as boxes in common terminals), score formatting and
  outcome messages
- art.py: course logo shown at the start of every game
- game.py: play_game (hit/stand, dealer draws below 17), play (restart
  loop, console clear, logo) and ask_yes_no with re-prompt; read, write
  and draw are injected so games can be scripted
- __main__.py: python -m blackjack entry point, exits cleanly on
  Ctrl+C/Ctrl+D
- constants.py: card ranks and suits, prompts and messages
- tests: 32 new unit and scripted end-to-end tests (35 in total)
- README: run instructions for python -m blackjack

Closes #7
Closes #8
Closes #9
Closes #10
Closes #11
Closes #12
Closes #13
Closes #14

Task: MIL-002#1
Task: MIL-002#2
Task: MIL-002#3
Task: MIL-002#4
Task: MIL-002#5
Task: MIL-002#6
Task: MIL-002#7
Task: MIL-002#8

src/blackjack/display.py

@@ -0,0 +1,61 @@
+"""!
+@file display.py
+@brief Turns cards, scores and outcomes into text for the console.
+"""
+
+from collections.abc import Sequence
+
+from blackjack.constants import (
+    BLACKJACK_MARKER,
+    CARD_RANKS,
+    CARD_SUITS,
+    LABEL_BLACKJACK,
+    MESSAGE_DRAW,
+    MESSAGE_LOSE,
+    MESSAGE_LOSE_BUST,
+    MESSAGE_LOSE_DEALER_BLACKJACK,
+    MESSAGE_WIN,
+    MESSAGE_WIN_BLACKJACK,
+    MESSAGE_WIN_DEALER_BUST,
+)
+from blackjack.rules import Outcome
+
+_OUTCOME_MESSAGES: dict[Outcome, str] = {
+    Outcome.DRAW: MESSAGE_DRAW,
+    Outcome.WIN: MESSAGE_WIN,
+    Outcome.WIN_BLACKJACK: MESSAGE_WIN_BLACKJACK,
+    Outcome.WIN_DEALER_BUST: MESSAGE_WIN_DEALER_BUST,
+    Outcome.LOSE: MESSAGE_LOSE,
+    Outcome.LOSE_DEALER_BLACKJACK: MESSAGE_LOSE_DEALER_BLACKJACK,
+    Outcome.LOSE_BUST: MESSAGE_LOSE_BUST,
+}
+
+
+def render_hand(cards: Sequence[int]) -> str:
+    """!
+    @brief Show a hand as emoji cards.
+    @param cards The card values in the hand.
+    @return The emoji faces separated by spaces.
+    """
+    return " ".join(
+        f"{CARD_RANKS[card]}{CARD_SUITS[index % len(CARD_SUITS)]}"
+        for index, card in enumerate(cards)
+    )
+
+
+def format_score(score: int) -> str:
+    """!
+    @brief Show a score for the player.
+    @param score A score from calculate_score (0 means blackjack).
+    @return The number, or the blackjack label.
+    """
+    return LABEL_BLACKJACK if score == BLACKJACK_MARKER else str(score)
+
+
+def outcome_message(outcome: Outcome) -> str:
+    """!
+    @brief Message announcing how the game ended.
+    @param outcome The outcome seen from the player.
+    @return The text to show.
+    """
+    return _OUTCOME_MESSAGES[outcome]