add test provenance columns and worker report fields

Add last_check/last_target columns to proxylist schema with migration.
Include checktype and target in V2 worker report payload.

dbs.py

@@ -98,6 +98,16 @@ def _migrate_last_seen(sqlite):
         sqlite.commit()
 
 
+def _migrate_last_check_columns(sqlite):
+    """Add last_check and last_target columns for test provenance tracking."""
+    for col, typedef in (('last_check', 'TEXT'), ('last_target', 'TEXT')):
+        try:
+            sqlite.execute('SELECT %s FROM proxylist LIMIT 1' % col)
+        except Exception:
+            sqlite.execute('ALTER TABLE proxylist ADD COLUMN %s %s' % (col, typedef))
+            sqlite.commit()
+
+
 def _migrate_uri_check_interval(sqlite):
     """Add adaptive check_interval column to uris table."""
     try:
@@ -371,7 +381,9 @@ def create_table_if_not_exists(sqlite, dbname):
             source_proto TEXT,
             source_confidence INT DEFAULT 0,
             protos_working TEXT,
-            last_seen INT DEFAULT 0)""")
+            last_seen INT DEFAULT 0,
+            last_check TEXT,
+            last_target TEXT)""")
         # Migration: add columns to existing databases (must run before creating indexes)
         _migrate_latency_columns(sqlite)
         _migrate_anonymity_columns(sqlite)
@@ -381,6 +393,7 @@ def create_table_if_not_exists(sqlite, dbname):
         _migrate_source_proto(sqlite)
         _migrate_protos_working(sqlite)
         _migrate_last_seen(sqlite)
+        _migrate_last_check_columns(sqlite)
         # Indexes for common query patterns
         sqlite.execute('CREATE INDEX IF NOT EXISTS idx_proxylist_failed ON proxylist(failed)')
         sqlite.execute('CREATE INDEX IF NOT EXISTS idx_proxylist_tested ON proxylist(tested)')