feat: implement external environmental data display components

- Add WeatherWidget for current weather conditions
- Add TideDisplay for tide times and heights
- Add WaterQualityIndicator for EPA water quality data
- Add BeachQualityDisplay for beach ratings and certifications
- Add BiodiversityInfo for marine biodiversity information
- Add EnvironmentalDataPanel composite component
- Create externalDataService for API integration
- Add types for external environmental data
- Create demo page at /demo/environmental-data
- Add comprehensive README documentation

Fulfills requirements 11.1, 11.2, 11.3, 11.4, 11.6, 11.7
Completes task 19 from implementation plan

src/pages/index.ts

@@ -8,3 +8,4 @@ export { default as LocationSelectorDemo } from './LocationSelectorDemo';
 export { ReportDetailDemo } from './ReportDetailDemo';
 export { WhyCleanPage } from './WhyCleanPage';
 export { UserProfilePage } from './UserProfilePage';
+export { EnvironmentalDataDemo } from './EnvironmentalDataDemo';