feat: add sunrise/sunset support to Homebridge plugin

Scheduler:
- Import sun.js calculator (already existed, never wired in)
- resolveSecs() maps -2=sunrise/-3=sunset sentinels + offset to actual seconds
- getTodaySun() reads stored location from store
- _loadSchedule(), _resumeAwayLoops(), _startAwayLoop() all resolve sun times

Server:
- Add /sun-times endpoint returning today's sunrise/sunset in seconds

UI:
- Start Time and End Time fields now show Fixed/Sunrise/Sunset dropdown
- Offset field (minutes before/after) shown when sun type selected
- Live preview shows today's base time + fires-at time with offset
- Save handler writes -2/-3 sentinels + startType/endType/startOffset/endOffset
- openDwmEdit() restores sun type and offset when editing existing rules

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/homebridge-plugin/homebridge-ui/server.js

@@ -28,6 +28,7 @@ const path       = require('path');
 const DwmStore   = require('../lib/store');
 const wemoClient = require('../lib/wemo-client');
 const axios      = require('axios');
+const { sunTimes: calcSunTimes } = require('../lib/sun');
 
 class DibbyWemoUiServer extends HomebridgePluginUiServer {
   constructor() {
@@ -122,6 +123,13 @@ class DibbyWemoUiServer extends HomebridgePluginUiServer {
       return this._store.getLocation();
     });
 
+    this.onRequest('/sun-times', async () => {
+      const loc = this._store.getLocation();
+      if (!loc?.lat || !loc?.lng) return { sunrise: null, sunset: null };
+      try { return calcSunTimes(loc.lat, loc.lng); }
+      catch { return { sunrise: null, sunset: null }; }
+    });
+
     this.onRequest('/location/set', async (loc) => {
       this._store.setLocation(loc);
       return { ok: true };