Tests, examples and run lines use placeholder credentials (#332)

Test fixtures pass "player"/"secret"; the run lines in `.cargo/config.toml`, the protocol
examples and the auth and world binaries show placeholders; the SRP probe example takes
--user and --pass instead of defaulting them. Built on macOS.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/benilla-protocol/examples/seed_classes.rs

@@ -13,7 +13,7 @@
 //!   --reload-templates  make the server re-read the premade tables before dressing
 //!   --host <h>        default `localhost`
 //!
-//! … -- one pone One --wipe --level 60 --tier phase6-bis --home --spread a
+//! … -- <account> <password> <Character> --wipe --level 60 --tier phase6-bis --home --spread a
 //! ```
 //!
 //! Without `--wipe` it skips classes the account already has. Creating needs no GM level;

crates/benilla-protocol/examples/srp_encoding_probe.rs

@@ -5,7 +5,7 @@
 //! whenever a value has one; cmangos does the same (`Sha1Hash::UpdateBigNumbers`).
 //!
 //! ```text
-//! cargo run --release -p benilla-protocol --example srp_encoding_probe -- --user one --pass pone
+//! cargo run --release -p benilla-protocol --example srp_encoding_probe -- --user U --pass P
 //! ```
 //!
 //! `--stress N` runs N ordinary fixed-width handshakes and reports the failure rate, waiting out
@@ -342,8 +342,8 @@ fn matrix(host: &str, user: &str, pass: &str, enc: Enc, title: &str) {
 
 fn main() -> Result<()> {
     let mut host = "localhost".to_string();
-    let mut user = "one".to_string();
-    let mut pass = "pone".to_string();
+    let mut user = String::new();
+    let mut pass = String::new();
     let mut stress = 0u32;
     let mut logons = 0u32;
     let mut args = std::env::args().skip(1);
@@ -357,6 +357,9 @@ fn main() -> Result<()> {
             other => return Err(anyhow!("unknown argument {other}")),
         }
     }
+    if user.is_empty() || pass.is_empty() {
+        return Err(anyhow!("--user and --pass are required"));
+    }
 
     // `--logon N` runs the shipped `logon` N times; every handshake must succeed, or its
     // ephemeral guarantee is not holding.