feat: implement server-side map clustering (#991)

* feat: meilisearch bounding box intersection and map filtering

* feat: tiered clustering and polyline filtering based on bounding box diagonal

Addressing review comments with optimized performance and data accuracy:
- Implemented a two-tiered search strategy (Summary vs. Detailed) to provide 100% accurate cluster counts while minimizing metadata traffic.
- Added a client-side ID-based cache to eliminate redundant network requests for trails already in memory.
- Introduced tiered 'detail shedding' that dynamically hides small trail lines when zooming out to maintain smooth panning performance.
- Fixed Svelte 5 reactivity issues to ensure clusters reappear instantly when trail detail is shed.
- Consolidated zoom thresholds into centralized constants for system-wide consistency.
- Updated Meilisearch configuration to support efficient ID-based filtering.

* feat: implement server-side map clustering using Meilisearch and Supercluster

- Implemented SvelteKit server-side clustering route at `/api/v1/search/trails/cluster` using the `supercluster` library.
- Integrated backend search results with the new clustering endpoint to improve performance for large trail datasets.
- Fixed Svelte 5 reactivity in `MapWithElevationMaplibre.svelte` by making `mapLoaded` reactive and fixing destructuring of `` map data.
- Removed obsolete client-side zoom constraints (`minzoom`/`maxzoom`) from `TrailLayer`, `PreviewLayer`, and `ClusterLayer` to allow dynamic visibility controlled by backend attributes.
- Fixed a bug where unauthenticated users generated invalid Meilisearch filters.
- Optimized map page performance by caching bounding box and filter values in the route loader.
- Updated `ClusterLayer` font to `Noto Sans Regular` to match available tileserver resources.

* feat: implement dynamic polyline visibility based on result density

- Replaced static zoom-based diagonal thresholds with a dynamic "Top N" approach for polyline visibility.
- Updated `/api/v1/search/trails/cluster` to mark only the top `MAP_MAX_POLYLINES` (default 100) trails by bounding box diagonal as "large".
- Modified `trails_search_bounding_box` store function to always fetch polylines for trails marked as large, regardless of zoom level.
- Removed obsolete `MAP_*_ZOOM_DIAGONAL_LIMIT` constants and simplified map layer constructors by removing tier-based filtering.
- Updated environment configurations and documentation to use the new `PUBLIC_MAP_MAX_POLYLINES` variable.

* refactor: remove obsolete zoom-based map clustering thresholds

Following the transition to dynamic server-side clustering based on result density (Top N polylines), this commit removes all remaining zoom-based thresholds and logic.

- Removed PUBLIC_MAP_LOW_ZOOM_THRESHOLD, PUBLIC_MAP_MEDIUM_ZOOM_THRESHOLD, and PUBLIC_MAP_HIGH_ZOOM_THRESHOLD environment variables.
- Removed the 'mapClusterMinZoom' user setting from the schema, models, and settings UI.
- Simplified the map component and MapLibre layer managers by removing unused 'clusterMinZoom', 'minZoom', and 'maxZoom' parameters.
- Cleaned up obsolete 'map-cluster-zoom-level' translation keys across all locales.
- Updated documentation to reflect the removal of these variables.

* chore: remove map clustering debug logs

* docs: update changelog and fix global zoom feature disappearance

* fix: address PR reviews and refine map cluster/preview visuals

* feat: implement configurable map cluster zoom and trail start marker settings

* feat: render single unclustered shedded trails as start markers instead of cluster circles

* minor fixes

* minor ui changes

* fix missing entries in map list

* remove redundant map clustering zoom clamp

* fix merge issues

* fix merge issues

* fixes

* hide popup for trails without details

* several improvements

* prevent import of client trail_store in server cluster code

* update changelog

---------

Co-authored-by: slothful-vassal <89943360+slothful-vassal@users.noreply.github.com>

docker/docker-compose.dev.yml

@@ -55,6 +55,7 @@ services:
       OVERPASS_API_URL: https://overpass-api.de
       VALHALLA_URL: https://valhalla1.openstreetmap.de
       NOMINATIM_URL: https://nominatim.openstreetmap.org
+      PUBLIC_MAP_MAX_POLYLINES: 100
     volumes:
       - uploads:/app/uploads
       # - ./data/about.md:/app/build/client/md/about.md

docker/docker-compose.prod.yml

@@ -55,6 +55,7 @@ services:
       OVERPASS_API_URL: https://overpass-api.de
       VALHALLA_URL: https://valhalla1.openstreetmap.de
       NOMINATIM_URL: https://nominatim.openstreetmap.org
+      PUBLIC_MAP_MAX_POLYLINES: 100
     volumes:
       - uploads:/app/uploads
       # - ./data/about.md:/app/build/client/md/about.md