feat: full layer deletion flow (MAPCO-7285)

[almog8k]

Question	Answer
Bug fix	✖
New feature	✔
Breaking change	✖
Deprecations	✖
Documentation	✖
Tests added	✔
Chore	✖

Related issues: MAPCO-7285

Overview

Implements the full-layer deletion flow in the overseer. A Delete_Layer job with a delete task drives ordered removal of a layer's metadata across every system that references it, then hands tile (and, later, artifact) cleanup off to the Cleaner via a downstream tiles-deletion task.

What this adds

Per-client deletion methods

• CatalogClient.deleteRecord — remove the catalog record.
• GeoserverClient: unpublishLayer → performs the geoserver unpublish.
• PolygonPartsMangerClient.deleteEntities — drop the polygon-parts entities.
• MapproxyApiClient.removeLayer — remove the layer from mapproxy (treats a 404 as already-removed / idempotent).

Storage / cache plumbing

• Split the S3 bucket config into artifactsBucket and tilesBucket (helm + config), guarded by tilesStorageProvider.
• MapproxyApiClient.getLayerCache returns the layer's cache object (directory + bucket) for the configured cache type, or undefined on 404.

DeleteLayerHandler (Delete_Layer / delete)

• Runs the four metadata-deletion steps in order, persisting each step's completion flag immediately so a redelivered task resumes from where it failed (does not repeat completed steps).
• Resolves the tiles location from the mapproxy cache before any deletion step and persists it into the task params — the deleteFromMapproxy step destroys the cache, so a redelivered task reads the location from its own params instead of re-querying a layer that no longer exists.
• Derives the Cleaner path from the mapproxy cache directory (not the catalogId): S3 drops the leading slash (object keys are lstripped by mapproxy), FS drops the first segment (the mapproxy PVC mount) so the Cleaner rejoins its own base path. S3 also carries the bucket (cache bucket_name, falling back to configured tilesBucket).
• Creates the downstream tiles-deletion cleaner task once all metadata steps complete, with an idempotency guard against duplicate creation on redelivery.

Wiring

• Registered the Delete_Layer job and delete task in the polling config and DI container.
• configUtil: extracted per-domain polling-task-type selection into getPollingTaskTypes.

Notes / follow-ups

• Artifacts-deletion task is deferred (TODO in the handler): mapproxy's GET /layer does not expose artifacts, so the existence source-of-truth and params shape are unresolved.

Tests

• Unit coverage for every new client method, the bucket-config split, getLayerCache, and the full DeleteLayerHandler flow (step ordering + per-step persistence, redelivery skip, FS/S3 path + bucket resolution, cleaner-task idempotency, and unresolvable-cache rejection).
• Full unit suite green (228 tests); tsc --noEmit, eslint, and prettier clean.

[CL-SHLOMIKONCHA]

Great!