feat: undo / delete logged entries (fix fat-fingered live logging)

Previously the only delete was whole-session, so a mis-logged stack or a
mis-parsed hand was stuck on the HUD. Now:

- undo_last tool ("scratch that") — deletes the most recent hand/stack/read/
  scar/confidence/reset in the live session; added to the Cash toolset.
- poker.delete_hand/stack/read/ritual + delete_entry dispatch + undo_last.
- DELETE /session/entry/{kind}/{id} endpoint.
- HUD: per-row × delete buttons on hands, confidence-bank, and scar-note rows
  (stack/read deletes via the tool). Row ids now surfaced in the hud() bundle.
- test_modes.py +2 (undo_last across kinds, tool handler); 46 green.

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

lyra/web/server.py

@@ -113,6 +113,13 @@ def create_app() -> FastAPI:
         bundle = await asyncio.to_thread(poker.hud)
         return bundle or {"session": None}
 
+    @app.delete("/session/entry/{kind}/{entry_id}")
+    async def delete_entry(kind: str, entry_id: int) -> dict:
+        """Delete one HUD entry (hand | stack | read | ritual) by id."""
+        ok = await asyncio.to_thread(poker.delete_entry, kind, entry_id)
+        logbus.log("info", "hud entry deleted", kind=kind, id=entry_id, ok=ok)
+        return {"ok": ok}
+
     @app.get("/history")
     async def history_page() -> FileResponse:
         """Browsable list of past poker sessions."""