Add asset plugin type and first-party Immich plugin

[slothful-vassal]

Summary

This PR introduces asset plugins, a new plugin category that connects wanderer to external media libraries, and ships Immich as the first integration: Immich suggests geotagged photos that match a trail or waypoint, and wanderer imports or links them as photo assets. This implements the feature requested in several issues (#160, #395). The plugin type is generic, so other libraries (e.g. PhotoPrism, #530) can follow without further core changes.

Data model & migration

• New assets collection plus link collections for trails, waypoints, and summit logs, with access rules, APIs, and hooks.
• Existing photos are migrated into asset records, and the legacy photos fields are removed from the trails, waypoints, and summit_logs collections — assets are now the single source of truth.
• Backward compatibility: API responses still expose a photos array, now computed from asset links, and federation/full-sync converts legacy photos file URLs from older instances into assets.

Plugin system

• New plugin type: "assets" with an asset_library.v1 capability; installed plugins are now categorized as trails or assets.
• Host-owned configured connectors, asset import limits, and thumbnail/import/materialize/repair/delete flows. Plugin schema, SDK, and docs updated accordingly.
• Two storage modes per asset plugin (photoMode): photos are either copied into wanderer (copy), or kept in the source library and referenced (link_private). Linked photos are materialized (copied in) before their target becomes public, and a guard prevents disabling a plugin while linked photos still depend on it.
• Because any public or federated trail always materializes its photos, link_private only saves storage for trails that stay private. The settings UI states this so the tradeoff isn't surprising.

Immich plugin

• Matches photos against the trail by capture time and GPS location; supports preview or original quality imports and an "own photos only" mode.
• Uses the generic storage modes above; defaults to copy.
• Least-privilege API key model — see upgrade notes below.

UI

• Photo search and selection from the media library in the trail editor, waypoint attachment, and waypoint creation directly from photos.
• Asset plugin settings, including admin actions to materialize, repair, or delete remote-linked photos in bulk (also triggered when disabling a plugin). These run asynchronously on the server; the settings page polls the job and shows a progress bar.
• New data maintenance pages: duplicates, photo metadata backfill, trails without photos, and orphaned photos.

Existing flows

• Trail imports and GPX uploads can auto-attach matching photos suggested by asset plugins; federation serializes/materializes asset photos; feed/profile/list APIs expose asset-backed photo URLs; GPX export includes asset photos; summit logs can link assets; trail merge preserves and reassigns photo assets.
• Replaces the bundled exif-js vendor copy with ExifReader. This is required here: photo matching needs HEIC/HEIF metadata, which must be read before heic2any strips it during conversion. It also leaves wanderer with a single maintained EXIF reader instead of two stacks.

Reviewer guide

The diff is large (~200 files), but much of it is mechanical — existing photo code paths updated to read and write through the new asset links. Suggested entry points, in reading order:

1. db/migrations/1778359896_created_assets.go — the assets collection, link collections, and legacy photo migration.
2. db/pluginsystem/manifest.go and plugins/schema/plugin.schema.json — the assets plugin type and asset_library.v1 capability.
3. db/routes/assets.go and db/routes/plugin_system_assets.go — asset APIs and the host-side search/import/materialize/repair/delete flows.
4. plugins/immich/ — the plugin itself (API client in immich.go, time/location matching in matching.go).
5. web/src/lib/components/photo/photo_picker.svelte — the central UI entry point for external photo selection.

Upgrade / review notes

• The migration converts existing trail, waypoint, and summit-log photos into asset records and then drops the photos fields from those collections. The down migration intentionally does not undo this; upgrade with a full backup.
• installed_plugins.type is updated so installed plugins are categorized as trails or assets.
• Immich API keys need only user.read, asset.read, asset.view, and asset.download. No write, delete, upload, album, library, or admin scopes are required.
• In link_private mode, photos stay backed by the source library only while the target remains non-public; publishing or federating a trail materializes (copies) its linked photos so public views can serve them safely. As a result, link_private reduces storage only for permanently-private trails.

Screenshots

(UI shown in German)

New Assets plugin category on the plugin settings page:

Immich plugin settings — storage mode, import size, auto-attach, and matching limits:

New data maintenance pages — duplicates, photo metadata backfill, trails without photos, and orphaned photos:

Photos as a source everywhere — waypoints can be created from photos, and photo pickers offer the media library next to local files:

The "waypoints from photos" dialog with source filter, time range, map preview, and photo preview:

Validation

Automated coverage was added or updated for asset migrations/share rules, asset helpers, federated asset identity, plugin manifests, asset plugin routes, asset merge, remote list/trail serialization, importer auto-attach, category preference filtering, and Immich matching.

Manual checks completed:

• Ran migrations against fresh and existing databases; verified the assets collection, asset plugin type, and existing trail plugins.
• Verified plugin listing/sorting, Immich configuration persistence, and enable/disable behavior.
• Verified Immich connection and previews with only user.read, asset.read, asset.view, and asset.download.
• Verified auto-attach defaults, explicit auto-attach opt-out, and time/location relevance filtering.
• Verified trail editor photo picker, waypoint photo matching, direct photo waypoint creation, save/reopen persistence, and rendering.
• Verified copied-photo storage mode.
• Smoke-tested an existing trail-plugin flow after the generic plugin changes.

Manual checks still pending — should be completed before merging:

• Invalid Immich URL/API key/missing-permission error handling.
• Failed or empty import cleanup, especially avoiding orphaned/empty waypoints.
• link_private access control for private trails, shared private trails, and publish transitions.
• Remote asset lifecycle states for missing/inaccessible Immich assets.
• Disable-plugin guard plus materialize/delete cleanup for linked remote photos.
• Trail merge with copied and remote-linked assets.

[slothful-vassal]

back to draft: try to implement as plugin