feat: unify DB and live waveform views with inline modal overlay

- Extract _buildWaveformCharts() shared renderer used by both live Events
  tab and new DB history modal (no duplicate chart-building code)
- Replace window.open(waveform_viewer.html) with openDbWaveformModal()
  that renders an inline overlay with full peaks bar, debug panel, and
  4-channel charts — same rendering path as the live device view
- Fix timestamp display for DB blobs (ISO string vs {display:...} object)
- Normalize old blob peak_values keys (tran/vert/long → tran_in_s etc.)
  for backward compat with pre-fix ACH blobs
- Close modal via × button, Esc key, or backdrop click; destroy Chart.js
  instances on close to free canvas memory
- Fix onclick UUID quoting in History table (UUIDs need quoted string arg)
- Fix ach_server.py peak_values key names to match viewer expectations
- Extract _fillDebugPanel() so same debug content works in both contexts

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

.gitignore

@@ -25,9 +25,4 @@ Thumbs.db
 
 # Analyzer outputs
 *.report
-claude_export_*.md
-
-# Frame database
-*.db
-*.db-wal
-*.db-shm
+claude_exp