Add app shell with Euchre and Sequence, LAN/Bluetooth play

First vertical slice: the whole shell plus two games playable end to end,
so every layer is exercised before the other nine games are built on it.

Games
- Euchre: bowers, ordering up, dealer discard, going alone, stick the
  dealer, and full scoring. Rule variants (deck size, points to win,
  stick the dealer, going alone) are toggles in game setup.
- Sequence: two-eyed and one-eyed jacks, free corners, locked sequences,
  the shared-chip limit, and dead-card exchange. Teams, players per team
  and the sequence target are toggles.
- The board layout in SequenceBoard is generated, not the commercial
  board — it holds every structural property the rules need, but does not
  match a physical board. Documented in docs/RULES-sequence.md.

Multiplayer
- One transport abstraction over newline-delimited JSON, implemented
  twice: LAN via NSD discovery and TCP, Bluetooth via Classic RFCOMM.
  A lobby advertises on both at once, so a table can mix them.
- Host-authoritative: clients send move intents, the host re-validates
  every one against the rules, and each client receives a state redacted
  for its own seat so hidden information never crosses the wire.
- Seats start as AI and are handed to people as they join, which is what
  makes any mix of humans and AI work without a separate code path.

Shell
- Main menu lists all eleven games; the nine without engines are marked
  coming soon and are driven entirely by GameCatalog.
- Settings: sound, animation speed (one multiplier drives card movement
  and AI thinking time), and OTA updates from the latest GitHub release.
- Layouts measure available space rather than assuming an orientation.

The game package is free of Android types, so the rules engines and AI
run under plain JUnit; 43 tests cover ranking, following suit, scoring,
sequence detection, redaction, wire round-trips and full random and AI
playthroughs.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_015qjfMiPUDshdKEUa6vxqzN

app/src/main/res/mipmap/ic_launcher_round.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Fallback round launcher icon for API < 26. -->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="48dp"
+    android:height="48dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#2E7D32"
+        android:pathData="M54,54m-54,0a54,54 0,1 1,108 0a54,54 0,1 1,-108 0" />
+    <path
+        android:fillColor="#111111"
+        android:pathData="M54,54m-26,0a26,26 0,1 1,52 0a26,26 0,1 1,-52 0" />
+    <path
+        android:fillColor="#000000"
+        android:pathData="M54,54m-20,0a20,20 0,1 1,40 0a20,20 0,1 1,-40 0" />
+</vector>