feat(prompting): Phase B step 2 — wire the sharded poker prompt into the pipeline

build_messages now shards poker_cash: injects poker_prompts.BASE + exactly ONE
fragment chosen by classify(user_msg, roster_handles), replacing the ~100-line
_CASH_CARD monolith. Roster handles are fetched fail-safe from the live session so
the READ-vs-HAND split is reliable. CASH.card set to "" (monolith kept only as the
distillation source, superseded). Other modes' single-card path unchanged.

Verified end-to-end: TAG-limp→READ, his-hand→HAND, table-broke→TABLE, tilt→MENTAL,
bare-stack→LOG, all with BASE always present. 5 injection/pipeline tests. Full
suite 196 green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyra/modes.py

@@ -240,7 +240,10 @@ TALK = Mode(
 CASH = Mode(
     key="poker_cash",
     label="Poker",
-    card=_CASH_CARD,
+    # Poker mode is SHARDED at the pipeline (lyra.poker_prompts: BASE + a per-message
+    # fragment), so no monolithic card here. _CASH_CARD is kept below only as the source
+    # material the fragments were distilled from — superseded, safe to delete later.
+    card="",
     tools=_CASH_TOOLS,
 )