DBSyn Phase 74 — Connection repair

Existing connection profiles decode without losing saved credentials.
Selecting another connection closes the previous MySQL session, clears stale results, and reloads schemas.
Editing and saving a profile disconnects its existing session and reloads databases.
Connection editor now includes integrated SSH forwarding using system OpenSSH and verified known_hosts.
Enable SSH and enter SSH host, SSH user, and optionally an identity file. MySQL host/port refer to the endpoint accessible from the SSH server (usually 127.0.0.1:3306).
SSH is key-based / agent-based (BatchMode=yes); password-based SSH authentication is not implemented.
Native direct MySQL TLS remains unimplemented. Direct remote connections remain blocked intentionally.
Tests and Xcode compilation must be run on macOS; Linux Swift syntax parse is not a macOS build.