Add MTGA Assistant: native Linux deck and game tracker

PySide6 app that follows MTG Arena's Player.log under Steam/Proton and shows
my remaining library with draw odds, my zones, and everything revealed about
the opponent (board, graveyard, exile, known hand/library, seen this match).

- Auto-detects the Steam library, Proton prefix log and MTGA install
- Card names/costs/types from MTGA's local SQLite card database
- Tracks card identity across zone changes, shuffles and Bo3 games
- Scryfall card images with a lazy, size-capped LRU disk cache
- Live log following with restart detection, plus --replay mode
- Flags log gaps where MTGA omits oversized game-state messages

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,25 @@
+[project]
+name = "mtga-assistant"
+version = "0.1.0"
+description = "Native Linux deck and game tracker for MTG Arena, driven by Player.log"
+readme = "README.md"
+requires-python = ">=3.12"
+dependencies = [
+    "PySide6-Essentials>=6.8",
+]
+
+[project.scripts]
+mtga-assistant = "mtga_assistant.app:main"
+
+[dependency-groups]
+dev = ["pytest>=8"]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/mtga_assistant"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]