fix: local echo overlay — 5 bugs fixed, 39-test suite, wrapping text survives tab switch

Root cause bugs fixed in local echo overlay:
1. Stored flushed text as string (_flushedText, _flushedTexts Map) to avoid reading stale terminal buffer
2. Overlay stays visible when pendingText empties but flushed > 0
3. Backspace into flushed text has immediate visual feedback
4. _flushedTexts.delete() added alongside _flushedOffsets.delete() in Enter/Ctrl+C/cleanup
5. OSC terminal responses (xterm color queries) no longer clear flushed text state —
   was triggered by _handleColorEvent → triggerDataEvent during buffer load after tab switch

Added comprehensive test suite (test/local-echo-user-test.mjs): 39 tests across 9 groups
including line wrapping, tab switch round-trips, backspace into flushed text, and more.
All 6 test suites pass (133 total assertions).

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "claudeman",
-  "version": "0.1588",
+  "version": "0.1591",
   "description": "The missing control plane for Claude Code - run 20 autonomous agents with real-time monitoring and session persistence",
   "type": "module",
   "main": "dist/index.js",