Naming Cleanup: Align registry names with AWS CLI conventions

[yimsk]

Summary

Normalize internal service/resource names in registry to align with AWS CLI conventions, preparing for future API layer (#64).

Current Inconsistencies

Directory	Registry Name	AWS CLI	Proposed
bedrockagentcore	bedrock-agentcore	bedrock-agent-runtime	bedrock-agent-runtime
risp	risp	ec2 / savingsplans	Keep as-is (intentional grouping)

Scope

• Change: Registry registration names only (register.go first argument)
• No change: Directory structure (Go package names cannot have hyphens)
• No change: Display names in UI (already user-friendly)

Why Now

• API URLs will be derived from registry names
• Fixing after API release would be a breaking change
• Low effort, high future impact

Tasks

• Audit all RegisterCustom() calls for naming consistency
• Update registry names to match AWS CLI where applicable
• Update aliases in defaultAliases() if needed
• Update defaultCategories() if service names change

Related

• Architecture: Separate API Layer from TUI for WebUI support #64 API Layer (depends on consistent naming)