Route command output through return values instead of printing directly

[digitalghost-dev]

Some commands print straight to stdout/stderr instead of returning their output, which splits the (string, error) contract and makes the output untestable.

Areas to update:

• types/DamageTable: return (string, error), threaded through TypesCommand
• search: surface fetch errors via WarningMessage instead of fmt.Printf() in Update
• pokemon: return wrapped image-download errors instead of printing them
• cli: currentVersion() returns a string

[digitalghost-dev]

Final round of the output-return cleanup started in #137 (also #162, #210, #144, #195). After this, command output is fully routed through return values. Two known exceptions remain by design: LatestFlag's direct print is deferred to #295, and the stdlib flag.Usage() help prints (cli.go + custom flagsets) are left as-is.