Add thesis status column for two-phase commit lifecycle tracking

app/storage/schema.sql

@@ -97,6 +97,7 @@ CREATE TABLE IF NOT EXISTS theses (
     defense_date DATETIME,
     published_at DATETIME,
     is_published BOOLEAN DEFAULT 0,
+    status TEXT NOT NULL DEFAULT 'active',
     baiu_link TEXT,
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,