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/tools.py

@@ -117,6 +117,25 @@ def _log_stack(args: dict, ctx: dict) -> str:
     return f"Stack ${amount:g} logged" + (f" (net {net:+.0f})." if net is not None else ".")
 
 
+def _undo_last(args: dict, ctx: dict) -> str:
+    what = (args.get("what") or "").strip().lower()
+    aliases = {"hands": "hand", "stacks": "stack", "reads": "read",
+               "scar_note": "scar", "confidence_bank": "confidence",
+               "scar note": "scar", "confidence": "confidence", "note": "ritual"}
+    what = aliases.get(what, what)
+    valid = ("hand", "stack", "read", "scar", "confidence", "reset", "ritual")
+    if what not in valid:
+        return f"Tell me what to undo — one of: {', '.join(valid)}."
+    try:
+        removed = poker.undo_last(what)
+    except ValueError:
+        return "No live session to undo anything in."
+    if not removed:
+        return f"Nothing logged to undo for '{what}'."
+    logbus.log("info", "undo last", what=what, removed=removed[:60])
+    return f"Scratched the last {what} — removed {removed}."
+
+
 def _scar_note(args: dict, ctx: dict) -> str:
     content = (args.get("content") or "").strip()
     if not content:
@@ -370,6 +389,13 @@ TOOLS.update({
     "add_buyin": {"handler": _add_buyin, "spec": _f(
         "add_buyin", "Record a rebuy / additional buy-in in the live session.",
         {"amount": {**_N, "description": "Amount added"}}, ["amount"])},
+    "undo_last": {"handler": _undo_last, "spec": _f(
+        "undo_last",
+        "Undo/delete the most recent logged entry in the live session when Brian says "
+        "'scratch that', 'delete that', 'that was wrong', etc. Specify what: 'hand', "
+        "'stack', 'read', 'scar', 'confidence', or 'reset'.",
+        {"what": {**_S, "description": "hand | stack | read | scar | confidence | reset"}},
+        ["what"])},
     "log_stack": {"handler": _log_stack, "spec": _f(
         "log_stack",
         "Record Brian's CURRENT total chip stack in the live session. Call whenever "