feat: edit hands from the viewer + "not my hand" disown

Addresses "no way to edit hands" and cleaning up misattributed ones:
- hand viewer (/hand/{id}) gets an "✎ Edit this hand" panel: position, cards,
  board, your net, tag, lesson → Save (existing PATCH), plus Delete.
- "Not my hand" → POST /hand/{id}/disown → poker.disown_hand clears the flat hero
  fields and rewrites structured with hero_involved=false, so a hand mislabeled as
  Brian's becomes a clean observed hand (replay stops showing him as hero).

1 test. Full suite 156 green.

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

lyra/poker.py

@@ -644,6 +644,28 @@ def update_hand(hand_id: int, **fields) -> dict | None:
     return get_hand(hand_id)
 
 
+def disown_hand(hand_id: int) -> dict | None:
+    """Reclassify a hand as OBSERVED (not Brian's) — fixes one that was mislabeled
+    as his. Clears the flat hero fields and rewrites the structured JSON with
+    hero_involved=false so the replay stops showing him as hero."""
+    h = get_hand(hand_id)
+    if not h:
+        return None
+    structured = h.get("structured")
+    if isinstance(structured, str):
+        structured = _safe_json(structured)
+    if isinstance(structured, dict):
+        structured = normalize_structured({**structured, "hero_involved": False})
+    conn = _c()
+    with conn:
+        conn.execute(
+            "UPDATE poker_hands SET position = NULL, hole_cards = NULL, result = NULL, "
+            "structured = ? WHERE id = ?",
+            (json.dumps(structured) if structured else None, hand_id),
+        )
+    return get_hand(hand_id)
+
+
 def list_hands(session_id: int | None = None) -> list[dict]:
     sid = _resolve(session_id)
     if sid is None: