correct the tiled inference chain and move runs off the request thread

Tile handling produced results that were wrong before any model quality
question arose:

- orthophoto tiles reached the model through PIL convert("RGB"), which
  truncates the high byte of a 16-bit product and treats a 4-band RGB+NIR
  tile's infrared channel as colour. Tiles are now read with rasterio, the
  visible bands are chosen explicitly, and values are percentile-stretched
  across all three bands together so hue is preserved;
- an object wider than the tile overlap was truncated by both tiles into two
  boxes that barely intersect, so IoU suppression kept both: two false
  positives and one missed footprint per seam building. Suppression now also
  compares overlap against the smaller box, and boxes cut by an interior tile
  edge are dropped in favour of the neighbouring tile's complete view;
- georeferencing fell back to an assumed EPSG:4326 when a manifest carried no
  CRS, producing geometry that renders plausibly in the wrong place. QA
  already refused such a tile; inference now fails closed too.

Segmentation QA scored candidates against every reference feature in the
dataset, so every building outside the inferred tiles counted as a false
negative. It now applies the same persisted tile coverage that detection QA
has always used, including the indexed ST_Intersects prefilter.

Duplicate suppression uses an STRtree instead of the O(n^2) scan, tiles are
predicted in batches of YOLO_BATCH_SIZE (a setting that existed but was never
read), and detection/segmentation runs can be queued through /run-async for a
polling background worker rather than holding an HTTP worker thread for
minutes of GPU work.

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

backend/app/core/config.py

@@ -350,6 +350,12 @@ class Settings(BaseSettings):
     )
     aoi_worker_enabled: bool = Field(default=False, validation_alias="GEOINTEL_AOI_WORKER_ENABLED")
     aoi_worker_poll_seconds: float = Field(default=2.0, ge=0.5, le=60.0, validation_alias="GEOINTEL_AOI_WORKER_POLL_SECONDS")
+    # Executes queued detection.run / segmentation.run jobs so tiled GPU
+    # inference never blocks an HTTP request.
+    analysis_worker_enabled: bool = Field(default=False, validation_alias="GEOINTEL_ANALYSIS_WORKER_ENABLED")
+    analysis_worker_poll_seconds: float = Field(
+        default=2.0, ge=0.5, le=60.0, validation_alias="GEOINTEL_ANALYSIS_WORKER_POLL_SECONDS"
+    )
     database_statement_timeout_ms: int = Field(default=5_000, validation_alias="DATABASE_STATEMENT_TIMEOUT_MS")
     yolo_enabled: bool = Field(default=False, validation_alias="YOLO_ENABLED")
     yolo_models_dir: str = Field(default="/app/models", validation_alias="YOLO_MODELS_DIR")
@@ -377,6 +383,9 @@ class Settings(BaseSettings):
     yolo_max_tiles: int = Field(default=100, validation_alias="YOLO_MAX_TILES")
     yolo_max_detections: int = Field(default=1000, validation_alias="YOLO_MAX_DETECTIONS")
     yolo_duplicate_iou_threshold: float = Field(default=0.5, ge=0.0, le=1.0, validation_alias="YOLO_DUPLICATE_IOU_THRESHOLD")
+    yolo_suppress_tile_edge_detections: bool = Field(
+        default=True, validation_alias="YOLO_SUPPRESS_TILE_EDGE_DETECTIONS"
+    )
     yolo_batch_size: int = Field(default=1, validation_alias="YOLO_BATCH_SIZE")
     yolo_seg_enabled: bool = Field(default=False, validation_alias="YOLO_SEG_ENABLED")
     yolo_seg_model_path: str | None = Field(default=None, validation_alias="YOLO_SEG_MODEL_PATH")