feat: optimize routes around accommodation, confirm note deletions (#1123)

Optimize day routes around the accommodation

When a day has an accommodation set, the route optimizer now treats it as
the day's home base: it optimizes a loop that leaves the hotel and returns
to it, so the stop nearest the hotel comes first. On a transfer day -
checking out of one hotel and into another - the route runs from the first
hotel to the second instead.

The optimizer also gained a 2-opt pass on top of the nearest-neighbor
ordering, which removes the crossings the greedy pass used to leave behind.
A new display setting ("optimize route from accommodation", on by default)
lets you turn the anchoring off.

Confirm before deleting notes

Deleting a plan note or a collab note now asks for confirmation first. On
phones and tablets the edit and delete icons sit close together and were
easy to mis-tap, which deleted notes with no way back.

client/src/types.ts

@@ -113,6 +113,7 @@ export interface Settings {
   show_place_description: boolean
   blur_booking_codes?: boolean
   map_booking_labels?: boolean
+  optimize_from_accommodation?: boolean
   map_provider?: 'leaflet' | 'mapbox-gl'
   mapbox_access_token?: string
   mapbox_style?: string
@@ -162,6 +163,12 @@ export interface Waypoint {
   lng: number
 }
 
+// Optional fixed start/end points for route optimization (e.g. the day's accommodation).
+export interface RouteAnchors {
+  start?: Waypoint
+  end?: Waypoint
+}
+
 // User with optional OIDC fields
 export interface UserWithOidc extends User {
   oidc_issuer?: string | null