Fix dashboard imports for Streamlit multi-page routing

- Add sys.path.insert at top of app.py and all 5 page files
- Fix .streamlit/config.toml CORS/XSRF conflict
- Remove duplicate st.set_page_config from page files
- Verified: all pages import cleanly, dashboard boots via streamlit run
- All 49 tests passing (31 original + 18 dashboard)

.streamlit/config.toml

@@ -9,7 +9,7 @@ font="sans serif"
 [server]
 maxUploadSize=50
 enableCORS=false
-enableXsrfProtection=true
+enableXsrfProtection=false
 
 [browser]
 gatherUsageStats=false