refactor: remove redundant reactive expression and implement pending state to handle UI selection synchronization

feat: implement case-insensitive URL parameter matching for country and station selection with startup prioritization

feat: implement dynamic map centering and zoom based on country and station selection

feat: persist station selection across filter updates using pending_station state

refactor: update station selection logic to drive UI components via reactive inputs instead of direct fetch triggers

feat: implement WMO climate observational dashboard with interactive map and station data visualization