feat: offer Nominatim entrance nodes as routing targets

A geocoded place drops its waypoint on the centroid, which for a large
site is nowhere a traveller can reach: BER's centroid sits on the
airfield, 1.5 km from the terminal doors, and the route ends on a slip
road. Nominatim reports a place's entrance nodes when asked
(`entrances=1`), so they are now offered as an alternative.

Clicking a door routes to it while the waypoint's pin stays on the place
that was searched for, joined by a dashed line. Every door stays on the
map, the chosen one marked, and clicking it again routes back to the
place.

The picker never chooses for the user. `entrance=main` records how a
building is laid out, not what a router can reach — the Pergamonmuseum
tags a main door the walking network stops 90 m short of, while its side
door is on the path — so acting on the tag would be confidently wrong
about as often as right.

Which doors are offered depends on two things:

  - Direction, from the wiki's one-way values. `entrance=exit` is "a
    one-way out" and so only usable at an origin; `entrance=entrance` is
    "a one-way in" and only at a destination. A via point is both
    arrived at and left from, so it takes neither.
  - The travel mode, from the door's own OSM access tags, following the
    access hierarchy (`motor_vehicle` > `vehicle` > `access`). Read live,
    so switching profile re-applies the rules to what is on screen.

Doors are named from their OSM `name` tag where they have one, and
labelled permanently. Where labels collide the whole colliding run
collapses into one listing every door in it; zooming in separates them
again. Labels live in a pane below the marker pane, because Leaflet
derives a marker's z-index from its latitude and a zIndexOffset alone
cannot keep a dot above them.

Also here:

  - The site outline is drawn beneath the doors, fetched only when the
    picker opens. It is thinned with Visvalingam-Whyatt, stopping as soon
    as the smallest surviving triangle would be visible, rather than with
    Nominatim's polygon_threshold: that tolerance is absolute degrees, so
    a value that usefully thins a 5 km airport flattens a 170 m building
    into five stray corners.
  - The gap between where a route can reach and its waypoint is now
    dashed throughout. Leaflet Routing Machine's default draws it as a
    solid casing with dashes on top, which against this app's heavy blue
    route reads as more route.
  - `continue_straight=true`, so OSRM leaves a via point by a different
    way instead of doubling back. Measured at 1575 m against 1524 m on a
    via at Hardenbergstrasse 36; a no-op without via points, and it still
    routes where the u-turn is unavoidable.
  - The persisted geocode cache moves to v2: entries predate the entrance
    data, the OSM identifiers and the access tags.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: github-actions[bot]

css/site.css

@@ -1118,3 +1118,81 @@ td.distance {
     pointer-events: none;
     z-index: 1000;
 }
+
+/* Entrance picker — alternative positions offered for a geocoded place.
+   Nominatim gives entrance nodes no name or ref, so the dot's position on the
+   map is the only thing that tells one apart from another. They are deliberately
+   smaller and flatter than the A/B waypoint pins: the pin shows where the route
+   actually starts, these only show where it could be moved to. */
+.osrm-entrance-marker {
+    box-sizing: border-box;
+    width: 18px;
+    height: 18px;
+    border-radius: 50%;
+    border: 3px solid #fff;
+    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
+    cursor: pointer;
+    transition: transform 0.1s ease-out;
+}
+
+.osrm-entrance-marker:hover {
+    transform: scale(1.35);
+}
+
+/* A door tagged entrance=main — the one most travellers are looking for. */
+.osrm-entrance-marker-main {
+    background-color: #2b7ac9;
+}
+
+/* Any other public entrance. */
+.osrm-entrance-marker-other {
+    background-color: #7fb2e5;
+}
+
+/* The centroid the geocoder originally returned, kept as a choice so a waypoint
+   moved to an entrance can always be moved back. */
+.osrm-entrance-marker-centre {
+    background-color: #8b8b8b;
+}
+
+/* The door the route currently runs to. Filled dark and ringed, so it reads as
+   chosen while every other door stays on the map and one click away. */
+.osrm-entrance-marker-selected {
+    background-color: #022bb1;
+    border-color: #fff;
+    box-shadow: 0 0 0 3px rgba(2, 43, 177, 0.35), 0 1px 3px rgba(0, 0, 0, 0.4);
+}
+
+/* Entrance labels. Permanent, so every door names itself without being
+   hovered. Owned by the picker rather than drawn as Leaflet tooltips: the
+   tooltip pane sits above the marker pane, which would put a label over the dot
+   it names. As markers they share the pane with the dots, and a lower
+   zIndexOffset keeps every dot on top. */
+.osrm-entrance-label {
+    /* Zero-sized, so the anchor is the door itself. */
+    width: 0;
+    height: 0;
+}
+
+.osrm-entrance-label-inner {
+    position: absolute;
+    left: 0;
+    bottom: 14px;
+    transform: translateX(-50%);
+    background-color: rgba(255, 255, 255, 0.94);
+    border-radius: 3px;
+    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.3);
+    color: #14243f;
+    font-size: 12px;
+    line-height: 1.35;
+    padding: 3px 7px;
+    pointer-events: none;
+    white-space: nowrap;
+}
+
+/* A merged label lists one door per line, so it cannot stay on one. */
+.osrm-entrance-label-merged .osrm-entrance-label-inner div + div {
+    border-top: 1px solid rgba(20, 36, 63, 0.12);
+    margin-top: 2px;
+    padding-top: 2px;
+}

i18n/de.js

@@ -16,5 +16,12 @@ module.exports = {
   'Bike': 'Fahrrad',
   'Car': 'Auto',
   'Foot': 'Fussgänger',
+  'Main entrance': 'Haupteingang',
+  'Entrance': 'Eingang',
+  'Centre of place': 'Ortsmitte',
+  'main entrance': 'Haupteingang',
+  'entrance': 'Eingang',
+  'Exit': 'Ausgang',
+  'exit': 'Ausgang',
   'Build': 'Build: '
 };

i18n/en.js

@@ -16,5 +16,12 @@ module.exports = {
   'Bike': 'Bike',
   'Car': 'Car',
   'Foot': 'Foot',
+  'Main entrance': 'Main entrance',
+  'Entrance': 'Entrance',
+  'Centre of place': 'Centre of place',
+  'main entrance': 'main entrance',
+  'entrance': 'entrance',
+  'Exit': 'Exit',
+  'exit': 'exit',
   'Build': 'Build: '
 };