feat: generate PASSWORD_HASH on the fly

* remove PASSWORD environment variable in favor of PASSWORD_HASH
* enhance password validity check server function
* update Dockerfile to include building a binary for generating hashed password
* update README with comprehensive Docker usage instructions hash generation

wg-password/src/main.rs

@@ -0,0 +1,39 @@
+fn main() {
+    let args = std::env::args();
+    let collect = args.collect::<Vec<String>>();
+    match collect.get(1) {
+        None => panic!("Your password was missing !"),
+        Some(password) => match bcrypt::hash(password, bcrypt::DEFAULT_COST) {
+            Err(err) => eprintln!("{}", err.to_string()),
+            Ok(hash) => println!("PASSWORD_HASH='{hash}'"),
+        },
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use assert_cmd::Command;
+    use predicates::prelude::*;
+
+    #[test]
+    fn test_missing_password() {
+        // Test when no password is provided
+        let mut cmd = Command::cargo_bin("wgpw").unwrap();
+        cmd.assert()
+            .failure()
+            .stderr(predicate::str::contains("Your password was missing !"));
+    }
+
+    #[test]
+    fn test_generate_password() {
+        // Test with a valid password
+        let mut cmd = Command::cargo_bin("wgpw").unwrap();
+        cmd.arg("my_password")
+            .assert()
+            .success()
+            .stdout(predicate::str::contains("PASSWORD_HASH='"));
+    }
+
+    // fn test_invalid_password() {
+    // }
+}