fix: address review feedback on PositionTracker and StrategyExecutor

- Fix fee attribution: distribute fees only to positions whose tick range
  contains the active tick at close time (in-range weight), not by raw
  liquidity. FLOOR is priced far below current tick and rarely earns fees;
  the old approach would over-credit it and corrupt capital-efficiency and
  net-P&L numbers. Fallback to raw-liquidity weighting with a WARN log
  when no position is in range.

- Warn on first-close skip: when _closePosition finds no open record
  (first recenter, before any tracking), log [TRACKER][WARN] instead of
  silently returning so the gap is visible in reports.

- Add tick range assertion: require() that the incoming close snapshot
  tick range matches the stored open record — a mismatch would mean IL
  is computed across different ranges (apples vs oranges).

- Fix finalBlock accuracy: logSummary now calls
  tracker.logFinalSummary(tracker.lastNotifiedBlock()) instead of
  lastRecenterBlock, so the summary reflects the actual last replay block
  rather than potentially hundreds of blocks early.

- Initialize lastRecenterBlock = block.number in StrategyExecutor
  constructor to defer the first recenter attempt by recenterInterval
  blocks and document the invariant.

- Extract shared FormatLib: _str(uint256) and _istr(int256) were
  copy-pasted in both PositionTracker and StrategyExecutor. Extracted to
  FormatLib.sol internal library; both contracts now use `using FormatLib`.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

onchain/script/backtesting/FormatLib.sol

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+pragma solidity ^0.8.19;
+
+/**
+ * @title FormatLib
+ * @notice Shared integer-to-string formatting helpers for backtesting log output.
+ *         Extracted to avoid copy-pasting the same logic across PositionTracker
+ *         and StrategyExecutor.
+ */
+library FormatLib {
+    /// @notice Format an unsigned integer as a decimal string.
+    function str(uint256 v) internal pure returns (string memory) {
+        if (v == 0) return "0";
+        uint256 tmp = v;
+        uint256 len;
+        while (tmp != 0) {
+            len++;
+            tmp /= 10;
+        }
+        bytes memory buf = new bytes(len);
+        while (v != 0) {
+            buf[--len] = bytes1(uint8(48 + v % 10));
+            v /= 10;
+        }
+        return string(buf);
+    }
+
+    /// @notice Format a signed integer as a decimal string (prefixed with '-' if negative).
+    function istr(int256 v) internal pure returns (string memory) {
+        if (v >= 0) return str(uint256(v));
+        return string.concat("-", str(uint256(-v)));
+    }
+}