Add SARscape SBAS prepared stack workflow

backend/migrations/008_timeseries_stack_plan_edges.sql

@@ -0,0 +1,36 @@
+-- Persist selected SBAS graph edges for time-series stack plans.
+
+CREATE TABLE IF NOT EXISTS timeseries_stack_plan_edges (
+    id SERIAL PRIMARY KEY,
+    plan_ref_id INTEGER NOT NULL REFERENCES timeseries_stack_plans(id) ON DELETE CASCADE,
+    master_plan_item_ref_id INTEGER NULL REFERENCES timeseries_stack_plan_items(id) ON DELETE SET NULL,
+    slave_plan_item_ref_id INTEGER NULL REFERENCES timeseries_stack_plan_items(id) ON DELETE SET NULL,
+    metric_cache_ref_id INTEGER NULL REFERENCES pairing_metric_cache(id) ON DELETE SET NULL,
+    master_scene_ref_id INTEGER NULL REFERENCES radar_data(id) ON DELETE SET NULL,
+    slave_scene_ref_id INTEGER NULL REFERENCES radar_data(id) ON DELETE SET NULL,
+    edge_rank INTEGER NOT NULL DEFAULT 0,
+    master_imaging_date VARCHAR(8) NULL,
+    slave_imaging_date VARCHAR(8) NULL,
+    temporal_baseline_days INTEGER NULL,
+    spatial_baseline_meters DOUBLE PRECISION NULL,
+    perpendicular_baseline_meters DOUBLE PRECISION NULL,
+    scene_overlap_ratio DOUBLE PRECISION NULL,
+    pair_aoi_overlap_ratio DOUBLE PRECISION NULL,
+    selection_reason VARCHAR(64) NULL,
+    selection_score DOUBLE PRECISION NULL,
+    selection_meta_json JSON NULL,
+    enabled BOOLEAN NOT NULL DEFAULT TRUE,
+    created_at TIMESTAMP NOT NULL DEFAULT NOW()
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS uq_timeseries_plan_edges_plan_rank
+    ON timeseries_stack_plan_edges (plan_ref_id, edge_rank);
+
+CREATE INDEX IF NOT EXISTS idx_timeseries_plan_edges_plan_enabled
+    ON timeseries_stack_plan_edges (plan_ref_id, enabled);
+
+CREATE INDEX IF NOT EXISTS idx_timeseries_plan_edges_plan_scenes
+    ON timeseries_stack_plan_edges (plan_ref_id, master_scene_ref_id, slave_scene_ref_id);
+
+CREATE INDEX IF NOT EXISTS idx_timeseries_plan_edges_metric_cache
+    ON timeseries_stack_plan_edges (metric_cache_ref_id);