feat: implement RSS subscriptions, downloader routing and local media checks

migrations/0002_downloader_instances.sql

@@ -0,0 +1,18 @@
+CREATE TABLE downloader_instances (
+    id TEXT PRIMARY KEY,
+    name TEXT NOT NULL,
+    kind TEXT NOT NULL CHECK (kind = 'qbittorrent'),
+    endpoint TEXT NOT NULL UNIQUE,
+    config TEXT NOT NULL
+);
+CREATE TABLE downloader_selection (
+    singleton INTEGER PRIMARY KEY CHECK (singleton = 1),
+    downloader_id TEXT REFERENCES downloader_instances(id)
+);
+INSERT INTO downloader_selection(singleton) VALUES (1);
+
+ALTER TABLE download_jobs ADD COLUMN downloader_id TEXT REFERENCES downloader_instances(id);
+ALTER TABLE download_jobs ADD COLUMN legacy_unassigned INTEGER NOT NULL DEFAULT 0;
+-- Existing jobs have no recorded owner. Do not assign them to an arbitrary new instance.
+UPDATE download_jobs SET legacy_unassigned = 1;
+CREATE INDEX jobs_downloader ON download_jobs(downloader_id, state);