refactor: remove DATABASE_URL auto-connection

src/main.rs

@@ -13,11 +13,9 @@ Usage:
   dbdash --sqlite PATH
   dbdash --help
 
-Run without a connection argument and without DATABASE_URL to connect in-app.
+Run without a connection argument to open the in-app connection screen:
-Otherwise DATABASE_URL supplies the PostgreSQL connection when no argument is given.
-Prefer the environment variable to keep passwords out of process arguments:
-  export DATABASE_URL='postgresql://user@localhost:5432/database'
   cargo run
+Use the in-app password field to keep credentials out of process arguments.
 
 Open an existing SQLite database file (read-only; missing files are not created):
   cargo run -- --sqlite ./database.sqlite
@@ -78,7 +76,7 @@ fn run() -> Result<()> {
                 .ok_or("--sqlite requires a database file path; see dbdash --help")?,
         )
     } else {
-        argument.or_else(|| std::env::var_os("DATABASE_URL"))
+        argument
     };
     if args.next().is_some() {
         return Err("unexpected extra arguments; see dbdash --help".into());