Silence CLI usage print and unify error handling

[mkysel]

Macroscope is automatically generating a new summary of this pull request including the latest commits...

Fixes #1114

[graphite-app]

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[macroscopeapp]

Silence CLI usage output and replace fatal process exits with error returns across xmtpd-cli commands, including setting a 15s context deadline in addRatesHandler

This change updates the xmtpd-cli to return errors instead of terminating the process and to suppress Cobra usage output on errors across admin, app-chain, key management, node registry, rate registry, settlement, and root commands. It also standardizes logger error wrapping and adjusts a context deadline to 15 seconds.

• Replace log.Fatalf/logger.Fatal with returned errors and logger.Error across handlers in admin_setup.go, appchain.go, key_management.go, node_registry.go, rate_registry.go, and settlement.go.
• Add SilenceUsage: true to parent and subcommands to suppress usage output on error in the same files.
• Convert addRatesCommand to RunE and update addRatesHandler to return errors with a 15s context deadline in rate_registry.go.
• Wrap errors with %w in cliLogger and hide the completion command in root.go.
• Refine messages and targets (e.g., include app-chain-gateway) and return fmt.Errorf for invalid targets in relevant handlers.

📍Where to Start

Start with the CLI error-handling pattern changes in addRatesHandler and command RunE wiring in rate_registry.go, then review representative handler conversions in appchain.go and settlement.go.

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Macroscope summarized d57cebe.