feat: save continue watching progress

migrations/011_add_continue_watching.sql

@@ -0,0 +1,13 @@
+CREATE TABLE IF NOT EXISTS continue_watching_entry (
+    id TEXT PRIMARY KEY,
+    user_id TEXT NOT NULL REFERENCES user(id) ON DELETE CASCADE,
+    anime_id INTEGER NOT NULL REFERENCES anime(id) ON DELETE CASCADE,
+    current_episode INTEGER,
+    current_time_seconds REAL NOT NULL DEFAULT 0,
+    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(user_id, anime_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_continue_watching_user_updated
+ON continue_watching_entry(user_id, updated_at DESC);