feat: Phase 1 Foundation & Dashboard implementation

- Core infrastructure: Zustand store, API client with mock fallback
- Mode detection: Port 8080 (kiosk) / 9090 (remote)
- Dashboard components: RainfallCard, ClockDisplay, CommStatus
- Header components: VoltageDisplay, BatteryStatus, LoginIndicator
- Data polling with visibility awareness
- Bundle size: ~100KB gzipped

Also adds README.md and WIKI.md documentation

.planning/phases/01-foundation-dashboard/01-01-SUMMARY.md

@@ -0,0 +1,73 @@
+# Plan 01 Summary - Core Infrastructure
+
+**Plan:** 01  
+**Phase:** 01-foundation-dashboard  
+**Completed:** 2026-03-13
+
+---
+
+## Tasks Completed
+
+### Task 1: Test Infrastructure
+- Created `vitest.config.ts` - Vitest configuration extending Vite
+- Created `src/test/setup.ts` - Test utilities and mocks
+- Added test scripts to `package.json`
+- Installed test dependencies: vitest, @testing-library/react, @testing-library/jest-dom, jsdom
+
+### Task 2: Zustand Sensor Store
+- Created `src/app/stores/sensorStore.ts`:
+  - SensorData interface with rainfall, voltage, station, communication types
+  - useSensorStore hook with actions: setSensorData, updatePollingInterval, setIsPolling, setError
+  - Selectors: selectRainfall, selectVoltage, selectStation, selectCommunication, selectTimestamp
+
+### Task 3: API Client with Mock Fallback
+- Created `src/app/api/client.ts`:
+  - fetchSensorData function with timeout and AbortController support
+  - generateMockSensorData for realistic mock data
+  - Automatic fallback to mock data on API failure
+
+### Task 4: Port-based Mode Detection
+- Created `src/app/hooks/useDisplayMode.ts`:
+  - useDisplayMode hook returning 'kiosk' or 'remote'
+  - Port 8080 → kiosk, Port 9090 → remote
+- Updated `src/app/App.tsx` to use display mode and initialize polling
+
+### Task 5: Data Polling with Cleanup
+- Created `src/app/hooks/useSensorPolling.ts`:
+  - Configurable polling interval (default 5 seconds)
+  - Page Visibility API support (pause when hidden)
+  - Proper cleanup with AbortController
+  - Start/stop/refresh controls
+
+---
+
+## Files Created/Modified
+
+| File | Status |
+|------|--------|
+| src/app/stores/sensorStore.ts | Created |
+| src/app/api/client.ts | Created |
+| src/app/hooks/useDisplayMode.ts | Created |
+| src/app/hooks/useSensorPolling.ts | Created |
+| src/app/App.tsx | Modified |
+| src/test/setup.ts | Created |
+| vitest.config.ts | Created |
+| package.json | Modified |
+
+---
+
+## Bundle Size
+
+- JS: 325KB uncompressed, 99KB gzipped
+- CSS: 92KB uncompressed, 15KB gzipped
+
+**Status:** Under 200KB limit (gzipped) ✓
+
+---
+
+## Notes
+
+- Mock data generation creates realistic values for testing
+- API client gracefully falls back to mock data
+- Polling pauses when tab is hidden to save resources
+- Mode detection enables responsive/kiosk layouts