Update documentation with recent test stability improvements

Add details about a floating-point precision fix for boluswizardpreview.test.js and note an infrastructure issue with test process hangs during server teardown in replit.md.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: cf276ff5-4001-4b44-93fe-7c9786ee4327
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Event-Id: 0e1264f9-9ae7-4b11-a0e7-658fe3d1f1ac
Replit-Helium-Checkpoint-Created: true

replit.md

@@ -143,11 +143,14 @@ npm run test:slow            # Tests with slow threshold logging
 **Summary:** ✅ **TESTS STABLE** - Stress testing (3-5 iterations per test file) shows 100% pass rate across all test files including api.shape-handling (now optimized).
 
 **Recent Fixes:**
+- `boluswizardpreview.test.js` - Fixed floating-point precision issue in `roundInsulinForDisplayFormat()` by adding epsilon (1e-9) before floor operation; test "set a pill to the BWP with infos" now stable
 - `api.shape-handling.test.js` - Fixed by optimizing server boot (beforeEach→before); now runs in ~6s with 172ms/test avg
 - `api.deduplication.test.js` - Fixed timeout issues by increasing timeout to 30s and optimizing cleanup
-- `boluswizardpreview.test.js` - All 10 tests now pass
 - `api3.renderer.test.js` - XML/CSV content type tests now pass
 
+**Known Infrastructure Issue:**
+- Full test suite runs may hang during server teardown (tick cycles continue after tests complete). Individual test files pass when run in isolation. This is a test cleanup issue, not test flakiness.
+
 **Flaky Test Status:** See `docs/test-specs/flaky-tests.md` for current status summary and improvement roadmap.
 
 #### Slow Tests