Reservation end time, route perf overhaul, assignment search fix

- Add reservation_end_time field (DB migration, API, UI)
- Split reservation form: separate date, start time, end time, status fields
- Fix DateTimePicker forcing 00:00 when no time selected
- Show end time across all reservation displays
- Link-to-assignment and date on same row (50/50 layout)
- Assignment search now shows day headers for filtered results
- Auto-fill date when selecting a day assignment
- Route segments: single OSRM request instead of N separate calls (~6s → ~1s)
- Route labels visible from zoom level 12 (was 16)
- Fix stale route labels after place deletion (useEffect triggers recalc)
- AbortController cancels outdated route calculations

client/src/components/shared/CustomDateTimePicker.jsx

@@ -172,7 +172,7 @@ export function CustomDateTimePicker({ value, onChange, placeholder, style = {}
   }
   const handleTimeChange = (t) => {
     const d = datePart || new Date().toISOString().split('T')[0]
-    onChange(t ? `${d}T${t}` : `${d}T00:00`)
+    onChange(t ? `${d}T${t}` : d)
   }
 
   return (

client/src/components/shared/CustomSelect.jsx

@@ -33,7 +33,29 @@ export default function CustomSelect({
 
   const selected = options.find(o => o.value === value)
   const filtered = searchable && search
-    ? options.filter(o => o.label.toLowerCase().includes(search.toLowerCase()))
+    ? (() => {
+        const q = search.toLowerCase()
+        const result = []
+        let currentHeader = null
+        let headerAdded = false
+        for (const o of options) {
+          if (o.isHeader) {
+            currentHeader = o
+            headerAdded = false
+            continue
+          }
+          // Match against label, searchLabel, or groupLabel
+          const haystack = [o.label, o.searchLabel, o.groupLabel].filter(Boolean).join(' ').toLowerCase()
+          if (haystack.includes(q)) {
+            if (currentHeader && !headerAdded) {
+              result.push(currentHeader)
+              headerAdded = true
+            }
+            result.push(o)
+          }
+        }
+        return result
+      })()
     : options
 
   const sm = size === 'sm'