[Feature]: MultiSite Support?

### Problem or opportunity

Many enterprise organizations operate Jira and Confluence on physically separated Atlassian sites (e.g., company-jira.atlassian.net and company-conf.atlassian.net) due to M&A, security policies, or billing structures.

Currently, the TWG CLI only supports storing authentication and context for a single site at a time.
This severely limits AI agents or MCPs from cross-referencing data. For instance, when an agent reads a Confluence page and finds a Jira ticket link, it fails to retrieve the Jira ticket details because the CLI is only authenticated to the Confluence site. Agents need a seamless way to query across multiple separated Atlassian sites.

### Proposed outcome

TWG CLI should natively support multiple site profiles or product-specific site routing.
Ideally, this could be achieved by:

- Multi-profile support: Allowing users to login and store multiple profiles (e.g., twg login --profile jira-site, twg login --profile conf-site) and execute commands with a profile flag (e.g., twg --profile conf-site confluence search ...).
- Product-level routing (Global Config): Allowing a single CLI configuration to map specific products to specific sites (e.g., routing all twg jira commands to Site A, and twg confluence commands to Site B automatically).

This would empower AI workflows to seamlessly navigate across fragmented Atlassian environments without manual context switching.

### Area

CLI command behavior

### Current workaround

_No response_