PINK kernel fix-of-fixes: slot-PnL repair plumbing

Review of PINK_ACCOUNTING_EXEC_FIX execution found the Phase 3.2 repair
path triply broken: (1) !closed guard blocked repair on terminal fills —
the common price-less case; (2) wrapper on_account_event was a raw FFI
passthrough so repairs never settled into published capital; (3) live
FILL_SETTLED carried no slot_id and realized_pnl=0 (pre-folded) — repair
was dead code. Fixes: repair allowed on closed slots (flag+dedup keep it
idempotent); wrapper settles the baseline diff on FILL_SETTLED-with-slot_id;
dedicated repair_realized_pnl field avoids double-folding the K-ledger;
_FakeKernelAccount fixture mirrors the Phase 1 anchor_to_exchange contract.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

prod/clean_arch/dita_v2/rust_backend.py

@@ -1156,7 +1156,33 @@ class ExecutionKernel:
         available_capital (E rules when present), k_capital, event_seq,
         capital_frozen (bool), duplicate_event (bool if deduplicated).
         """
-        return _get_rust().on_account_event(self._backend, event)
+        result = _get_rust().on_account_event(self._backend, event)
+        # Settle slot-level repairs into published capital. The Rust
+        # FILL_SETTLED handler may add exchange realized PnL to a slot whose
+        # exit leg booked 0 (price-less fill); the settle-baseline diff
+        # otherwise only runs in on_venue_event, so a repair — especially on
+        # an already-CLOSED slot (terminal fill, the common case) — would
+        # never reach AccountProjection.capital.
+        try:
+            kind = str(event.get("kind", "") or "").upper()
+            sid_raw = event.get("slot_id")
+            if kind == "FILL_SETTLED" and sid_raw is not None:
+                sid = int(sid_raw)
+                if 0 <= sid < self.max_slots:
+                    slot = self._get_slot(sid)
+                    incremental = slot.realized_pnl - self._last_settled_pnl.get(sid, 0.0)
+                    if abs(incremental) > 1e-12:
+                        self.account.settle(incremental)
+                        self._last_settled_pnl[sid] = slot.realized_pnl
+                        self.account.observe_slots(
+                            [self._get_slot(i) for i in range(self.max_slots)]
+                        )
+                        current = self._get_slot(sid)
+                        self.projection.write_slot(current)
+                        self.zinc_plane.write_slot(current)
+        except Exception:
+            pass
+        return result
 
     # ------------------------------------------------------------------
     # Snapshot / restore — session-to-session state continuity