Avoid specifying already specified homeserver for username and room

cargo run -- --login password

    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.28s
     Running `target/debug/matrix-commander-rs --login password`
Enter your Matrix homeserver (e.g. https://some.homeserver.org): https://matrix.org 
Enter your full Matrix username (e.g. @john:some.homeserver.org): @overclock3000
2026-07-02T10:51:02.270827Z ERROR matrix_commander_rs: Error: Invalid username format!
Enter your full Matrix username (e.g. @john:some.homeserver.org): @overclock3000:matrix.org
Enter Matrix password for this user: 
Enter your desired name for the Matrix device that is going to be created for you (e.g. matrix-commander-rs): matrix-commander-rs_oracle_power_ubuntu_key_storage_disabled
Enter name of one of your Matrix rooms that you want to use as default room  (e.g. !someRoomId:some.homeserver.org): !fOZKtmbCJlBYsrJEag
2026-07-02T10:55:29.129841Z ERROR matrix_commander_rs: Error: Invalid room name format for '!fOZKtmbCJlBYsrJEag'! Room name must start with '!' and contain exactly one ':'.
Enter name of one of your Matrix rooms that you want to use as default room  (e.g. !someRoomId:some.homeserver.org): !fOZKtmbCJlBYsrJEag:matrix.org

No relevant issue or pull request for username, name format and default room.

I have read issues/5 which does not seem relevant.