Fix MySQL /var/log/mysql missing and password shell injection

Two bugs revealed by the first successful async run:

1. MySQL containers crash with "mkdir: cannot create directory
   /var/log/mysql: Permission denied" because slow_query_log_file
   references /var/log/mysql/slow-queries.log but the directory
   does not exist in the base image and MySQL runs as a non-root
   user. Create it with correct ownership in the Dockerfile RUN layer.

2. generate_mysql_superset_password() used string.punctuation which
   includes single-quotes, backslashes, braces, and carets. These
   characters break the Python string literals in run_python_container_command
   where the password is interpolated with str.format() into a
   single-quoted Python expression, causing a SyntaxError. Restrict
   the charset to safe special characters that do not conflict with
   Python or shell quoting.

Author: szachovy

services/mysql-server/Dockerfile

@@ -39,6 +39,14 @@ RUN \
   mkdir \
     "/etc/mysql/ssl" \
   && \
+  mkdir \
+    --parents \
+      "/var/log/mysql" \
+  && \
+  chown \
+    mysql:mysql \
+      "/var/log/mysql" \
+  && \
   apt-get \
     clean \
   && \

src/crypto.py

@@ -65,7 +65,7 @@ def generate_mysql_root_password() -> str:
 
     @staticmethod
     def generate_mysql_superset_password() -> str:
-        charset = string.ascii_letters + string.digits + string.punctuation
+        charset = string.ascii_letters + string.digits + "!@#$%&*-_=+[]<>?"
         return "".join(secrets.choice(charset) for _ in range(24))
 
     @staticmethod