refactor: simplify key command config handling

[gjermundgaraba]

Summary

• keep key-only commands independent of the config file
• preflight config population and roll back new keys when config persistence fails
• make config replacement atomic and remove one-caller config helpers

Tests

• make lint-fix
• go test ./internal/config ./cmd/ibc -count=1

[greptile-apps]

Greptile Summary

The PR separates key-only commands from config loading, preflights optional signer population, rolls back newly written keys when config persistence fails, and replaces direct config writes with temporary-file renames.

• Removes optional-config setup from key creation, import, display, and listing.
• Consolidates key storage and optional signer registration in saveNamedKey.
• Preserves existing config permissions while replacing config files atomically.
• Adds focused tests for config population, alias conflicts, invalid config, and rollback.

Confidence Score: 4/5

The config replacement behavior should be fixed before merging because persisting configuration through a symlink silently breaks the link and leaves its target stale.

The new temporary-file rename changes established path semantics for every config-writing command by replacing an existing symbolic link with a regular file.

Files Needing Attention: link/internal/config/config.go

Important Files Changed

Filename	Overview
link/cmd/ibc/keys.go	Consolidates key persistence and optional config population with preflight alias checks and rollback on config-write failure.
link/internal/config/config.go	Introduces temporary-file replacement for config writes, but the rename replaces existing configuration symlinks rather than updating their targets.
link/cmd/ibc/config.go	Removes the optional-config helper and applies the database flag override directly during required config setup.
link/cmd/ibc/main.go	Delegates required private-key flag validation to Cobra.
link/cmd/ibc/keys_test.go	Adds coverage for signer population, alias conflicts, invalid configuration, and key rollback.

_{Reviews (1): Last reviewed commit: "simplify key command config handling" | Re-trigger Greptile}