consume only artifacts the runtime produced

tile_manifest_path arrives in the detection and segmentation request and was
read straight off disk, and a manifest entry may name an absolute tile path.
That makes an API field an unbounded reference to the host filesystem, and it
contradicts the rule the persistence model rests on: only a governed,
runtime-produced artifact may be consumed, and a file outside the storage root
is not one.

Both the manifest and every tile it names now resolve under STORAGE_ROOT.
Resolution happens before the comparison, so ".." cannot climb out and a
sibling that merely shares a name prefix does not pass.
GEOINTEL_ALLOW_EXTERNAL_ARTIFACT_PATHS opts out for provisioning workflows that
stage tiles before ingest.

The check honours the Settings the caller is operating under rather than the
process-wide ones, because every analysis path already threads its own.

The affected tests write manifests into tmp_path, so they now declare tmp_path
as the storage root — which is what a deployment does, and makes the fixtures
more honest than they were.

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

backend/app/core/config.py

@@ -49,6 +49,11 @@ class Settings(BaseSettings):
         validation_alias="DATABASE_URL",
     )
     storage_root: str = Field(default="./storage", validation_alias="STORAGE_ROOT")
+    # Analysis consumes only artifacts under storage_root. Provisioning
+    # workflows that stage tiles elsewhere before ingest can opt out.
+    allow_external_artifact_paths: bool = Field(
+        default=False, validation_alias="GEOINTEL_ALLOW_EXTERNAL_ARTIFACT_PATHS"
+    )
     max_upload_mb: int = Field(default=500, validation_alias="MAX_UPLOAD_MB")
     orthophoto_enabled: bool = Field(default=True, validation_alias="ORTHOPHOTO_ENABLED")
     orthophoto_wms_url: str = Field(