ux: standardize success output format across commands

[owenwahlgren]

Description

Success output varies inconsistently across commands:

• Keys: "Key imported successfully!" with structured output
• Subnet create: "Subnet created successfully!" + "Subnet ID: ..."
• Validator add: Just "TX ID: ..." (no success message)
• Transfer: "Transfer complete!"

Suggested standard format

[Action] successful!
  [Structured details...]
TX ID: ...

Files affected

All cmd/*.go files

Severity

Low - cosmetic consistency

Source

CLI UX audit (2026-02-09)