fix(database): use per-user admin passwords

drizzle/0003_lifeos_admin_credentials.sql

@@ -0,0 +1,7 @@
+CREATE TABLE lifeos_admin_credentials (
+  user_id TEXT PRIMARY KEY,
+  salt TEXT NOT NULL,
+  password_hash TEXT NOT NULL,
+  iterations INTEGER NOT NULL,
+  updated_at TEXT NOT NULL
+);