feat(phase-8): add deck_builder package init with public API

src/commander_ai_lab/deck_builder/__init__.py

@@ -1,2 +1,18 @@
-# deck_builder package
+"""
+Commander AI Deck Builder
+~~~~~~~~~~~~~~~~~~~~~~~~~
+Top-level package for the deck builder module.
+
+Usage::
+
+    from commander_ai_lab.deck_builder import build_deck, BuildRequest
+
+    result = build_deck(BuildRequest(commander_name="Atraxa, Praetors' Voice"))
+"""
+
 __version__ = "0.1.0"
+
+from .pipeline import build_deck
+from .core.models import BuildRequest, BuildResult
+
+__all__ = ["build_deck", "BuildRequest", "BuildResult", "__version__"]