[datlechin]

Why

Release criterion 9: no message the user cannot have translated. The SSH host, username and jump host checks showed the ssh crate's English detail, and a failed write of the saved connections showed the storage error's English text.

Change

• SshFailure::InvalidDestination carries an SshDestinationProblem (part, character, port text). The app words each one.
• A failed write of the saved connections, the edit-save toast and the reset toast word the I/O error by its kind: disk full, read-only, not allowed.
• A task panic, an export encoder failure and an SSH failure with no sentence of its own show the app's words. The detail goes to the log.

Verified

New tests pin each mapping in core, ssh, session and app. Changed on purpose: each_failure_says_what_happened, only_a_problem_with_the_chosen_file_blames_it, a_bad_row_names_the_row_it_is_in, destination_rejects_empty_leading_dash_whitespace_control_and_port_zero (now each_refusal_names_the_part_and_what_is_wrong_with_it).

Not in this PR

• The ssh crate's runtime directory details, its exit-status prefix, a failed ssh -G, an ssh that would not start and a master that exited silently; a TLS failure the app does not classify. Listed in ROADMAP.md, criterion 9.