fix: address CodeRabbitAI review comments for conversation history

- Fix duplicate onConversationCreated callbacks by tracking activeConversationId
- Fix history loss when switching conversations with Map-based deduplication
- Disable input while conversation is loading to prevent message routing issues
- Gate WebSocket debug logs behind DEV flag (import.meta.env.DEV)
- Downgrade server logging from info to debug level for reduced noise
- Fix .gitignore prefixes for playwright paths (ui/playwright-report/, ui/test-results/)
- Remove debug console.log from ConversationHistory.tsx
- Add staleTime (30s) to single conversation query for better caching
- Increase history message cap from 20 to 35 for better context
- Replace fixed timeouts with condition-based waits in e2e tests

.gitignore

@@ -64,7 +64,7 @@ coverage.xml
 .hypothesis/
 .pytest_cache/
 nosetests.xml
-./ui/playwright-report
+ui/playwright-report/
 
 # mypy
 .mypy_cache/
@@ -143,4 +143,4 @@ Pipfile.lock
 .tmp/
 .temp/
 tmpclaude-*-cwd
-./ui/test-results
+ui/test-results/